Comparison of Outcomes Following Glaucoma Drainage Tube Surgery Between Primary and Secondary Glaucomas, and Between Phakic and Pseudophakic eyes

PURPOSE

To report outcomes of glaucoma drainage device (GDD) surgery based on primary or secondary glaucoma diagnosis and lens status.

DESIGN

Single-center, retrospective, consecutive cohort study.

METHODS

University of Florida patients aged 18 to 93 years who underwent nonvalved GDD surgery between 1996 and 2015 with a minimum of 1-year follow-up were examined. Of the 186 eyes of 186 patients enrolled, 108 had a primary glaucoma and 78 a secondary glaucoma diagnosis. Excluding 13 aphakic patients, 57 eyes were phakic and 116 pseudophakic. Mean intraocular pressure (IOP), mean number of medications, visual acuity (VA), surgical complications, and failure (IOP ≥18 mm Hg, IOP <6 mm Hg, reoperation for glaucoma, or loss of light perception) were the main outcome measures.

RESULTS

No significant difference was noted in mean IOP and mean medication use (12.8 ± 4.5 and 13.0 ± 6.6 mm Hg on 2.0 ± 1.2 and 1.5 ± 1.1 medication classes, respectively), mean VA (1.08 ± 0.98 and 0.94 ± 0.89, respectively), failure, or numbers of complications and reoperations (P > 0.05) between eyes with primary and secondary glaucomas at up to 5 years postoperatively. Comparison of phakic and pseudophakic eyes showed a statistically significant higher success rate for the pseudophakic patient group at the ≥18 mm Hg upper limit and <6 mm Hg lower limit (P = 0.01), and significantly fewer eyes required reoperation to lower IOP (6.9% vs 23%).

CONCLUSIONS

GDD surgery appears equally effective for secondary glaucomas as for primary glaucomas, and has a better outcome for pseudophakic eyes than phakic eyes.

Bilateral anterior segment dysgenesis and persistent fetal vasculature associated with terminal 10q26 deletion

Deletion of the 26q position on chromosome 10 results in a syndrome with well-documented systemic phenotypes. There are few reports of ophthalmic manifestations in terminal 10q26 deletion. We report a 4-week-old boy with terminal 10q26 deletion who had extensive ophthalmic abnormalities, including bilateral anterior segment dysgenesis and bilateral persistent fetal vasculature, with microphthalmia, microcornea, iris corectopia, congenital cataracts, and posterior embryotoxon.

Comparison of Outcomes of Glaucoma Drainage Implant Surgery With or Without Prior Failed Trabeculectomy

PRECIS

A comparison of 186 glaucoma patients with mixed diagnoses who underwent nonvalved glaucoma drainage device (GDD) implant surgery showed similar long-term intraocular pressure (IOP), medication, and visual acuity (VA) outcomes between those with prior failed trabeculectomy surgery versus those without.

PURPOSE

The purpose of this study was to evaluate whether prior failed trabeculectomy adversely affects the outcome of glaucoma tube surgery.

PATIENTS AND METHODS

A total of 186 eyes of 186 patients who underwent a nonvalved GDD implant surgery by a single surgeon between 1996 and 2015 at a University practice were included. Patients were of mixed diagnoses and over 18 years old. Before the GDD surgery, 65 had a previous failed glaucoma filtering surgery and 121 had no prior glaucoma surgery. Demographic information, preoperative and postoperative IOP, medication, VA, and complications were collected from chart review.

RESULTS

No significant difference was noted in mean IOP and mean medication use (13.0 and 12.6 mm Hg on 2.0 and 1.7 medication classes at 5 y postoperatively, respectively), mean VA and change in VA from baseline, or numbers of complications (P>0.05), between eyes that had a prior failed filtration surgery and those that had not. Kaplan-Meier plots for failure over 5 years using a lower limit of <5 mm Hg and an upper limit of ≥18, ≥15, or ≥12 mm Hg did not show a significant difference between groups. Subanalyses were performed to examine only primary glaucoma eyes and results were similar. Further group subanalyses comparing those with baseline IOP ≥25 or <25 mm Hg, age 65 and above or below 65 years and those specifically with Baerveldt 350 mm2 implants also did not show significant differences.

CONCLUSION

Prior failed filtration surgery does not appear to affect the outcome of future GDD surgery.

A new, minimally invasive procedure for dogs with encapsulated Ahmed drainage implants and elevated intraocular pressures: A case series

OBJECTIVE

To describe a novel, minimally invasive method for re-establishing aqueous humor outflow in dogs with refractory glaucoma after fibrous encapsulation of their Ahmed drainage implants.

PROCEDURE

Three dogs (4 eyes) underwent trans-capsular implantation of an Alcon EX-PRESS^® glaucoma filtration device under sedation (2 dogs) or general anesthesia (1 dog). After rotating the eye downwards, a 2 mm incision was made in the conjunctiva/Tenon's capsule overlying the encapsulated Ahmed plate, and later closed with absorbable suture. All eyes received subconjunctival mitomycin-C 0.02 mg.

RESULTS

Mean post-operative follow-up was 341 days (range: 77-530). All eyes were hypertensive pre-operatively (mean IOP: 31.25 ± 7.14 mmHg) despite receiving topical latanoprost (4/4), timolol (4/4), carbonic anhydrase inhibitors (4/4), and demecarium bromide (2/4). Two eyes (dogs 1 and 2) were visual pre-operatively, while 2 eyes (dog 3) displayed equivocal or no vision. Post-operatively, all eyes received timolol and a carbonic anhydrase inhibitor. Other anti-hypertensive medications were discontinued. Immediately following surgery, all eyes were mildly hypotensive (mean IOP: 5.75 ± 1.71 mm Hg). Two of 4 eyes were normotensive and visual until days 90 (dog 2) and 530 (dog 1) (IOP range: 10-16 mm Hg). One eye (dog 3) was normotensive for approximately 150 days, and then hypertension returned. One eye (dog 3) from the start displayed severe uveitis, hypertensive episodes, and was phthisical by the end of follow-up.

CONCLUSIONS

Trans-capsular EX-PRESS^® implantation is a minimally invasive procedure for treatment of refractory glaucoma in dogs with encapsulated Ahmed drainage implants, and further investigation is warranted.

Attaining Intraocular Pressure of ≤10 mm Hg: Comparison of Tube and Trabeculectomy Surgery in Pseudophakic Primary Glaucoma Eyes

PURPOSE

The aim of this study is to evaluate whether trabeculectomy with antimetabolites or glaucoma drainage device (GDD) surgery is more likely to achieve an intraocular pressure (IOP) ≤10 mm Hg.

DESIGN

Retrospective, nonrandomized, cohort study of pseudophakic, primary glaucoma patients.

METHODS

53 pseudophakic patients underwent trabeculectomy and 65 received GDD at the University of Florida by one surgeon between 1993 and 2015. The main outcome measures were mean IOP and percentage of patients obtaining an IOP ≤10 mm Hg for up to 5 years postoperatively. A subgroup undergoing a first time glaucoma surgery was also analyzed because there were more redo glaucoma procedures in the GDD group.

RESULTS

Over 5 years, the mean annual IOP for the trabeculectomy eyes was between 6.9 and 7.8 mm Hg on an average of 0.2 medications, and that for GDD eyes was between 11.4 and 12.1 mm Hg on a mean of 1.6 to 1.9 medications (P < 0.002). A significantly higher percentage of trabeculectomy eyes than GDD eyes achieved a pressure of ≤10 mm Hg, for years 1 to 4 (P < 0.05). Visual acuity (VA) change was not statistically different between the groups, both for mean logMAR acuity and percentage of patients that lost ≥2 Snellen lines. Complication rates were similar between the groups. Postoperative VA change was similar for eyes achieving low IOP ≤5 mm Hg and those eyes with an IOP ≥10 mm Hg.

CONCLUSIONS

Trabeculectomy provided significantly lower IOP for 5 years postoperatively in pseudophakic primary glaucoma patients, and was more likely to achieve an IOP ≤10 mm Hg.

Modulating Ocular Scarring in Glaucoma Filtration Surgery Using the Epigenetic Adjunct Suberoylanilide Hydroxamic Acid

Aim

The aim of this study is to assess the effectiveness of suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor (HDI) with a broad spectrum epigenetic activity, in improving filtration bleb survival as an adjunct therapy to glaucoma filtration surgery (GFS) in the rabbit model.

Materials and methods

Eighteen New Zealand White rabbits underwent GFS in the left eye and were randomized to receive either a subconjunctival (SC) injection of 0.1 mL SAHA (9.25 μg/mL) or balanced saline solution (BSS) at the end of surgery, or a 3-minute intraoperative topical application of 0.4 mg/mL mitomycin-C (MMC). Bleb survival and histology were compared.

Results

Blebs of rabbits receiving injections of SAHA survived an average (mean ± SD) of 23.2 ± 2.7 days. SAHA rabbits showed a nonsignificant improvement over rabbits that received an injection of BSS, which had a mean survival time of 19.7 ± 2.7 days (p = 0.38) according to a one-way analysis of variance (ANOVA). Eyes receiving intraoperative topical MMC survived an average of 32.5 ± 3.3 days, which is significantly longer than both the control group treated with BSS (p = 0.01) and the experimental group treated with the SAHA (p = 0.0495). SAHA was well tolerated and showed no significant avascularity, necrosis, or conjunctival thinning.

Conclusion

Although it was well tolerated, a single intraoperative injection of SAHA did not significantly prolong bleb survival in the rabbit model.

Clinical significance

Epigenetic adjuncts hold promise for improving GFS outcome; however, future studies must continue to examine different administration protocols and dosages to substantiate their efficacy.

How to cite this article

Rodgers CD, Lukowski ZL, et al. Modulating Ocular Scarring in Glaucoma Filtration Surgery Using the Epigenetic Adjunct Suberoylanilide Hydroxamic Acid. J Curr Glaucoma Pract 2019;13(1):37–41.

The impact of conjunctival flap method and drainage cannula diameter on bleb survival in the rabbit model

PURPOSE

To examine the effect of cannula diameter and conjunctival flap method on bleb survival in rabbits undergoing cannula-based glaucoma filtration surgery (GFS).

METHODS

Twelve New Zealand White rabbits underwent GFS in both eyes. The twenty-four eyes were divided into four groups. Two of the four groups (N = 12) received limbus-based conjunctival flaps (LBCF), and the other two (N = 12) received fornix-based conjunctival flaps (FBCF). Six FBCF rabbit eyes were implanted with 22-gauge drainage tubes, and the other six were implanted with 26-gauge tubes. Likewise, six LBCF rabbits received 22-gauge drainage tubes and six received 26-gauge tubes. Filtration blebs were evaluated every three days by a masked observer. Bleb failure was defined as the primary endpoint in this study and was recorded after two consecutive flat bleb evaluations.

RESULTS

Group 1 (LBCF, 22- gauge cannula) had a mean bleb survival time (Mean ± SD) of 18.7 ± 2.9 days. Group 2 (LBCF, 26-gauge cannula) also had a mean bleb survival time of 18.7 ± 2.9 days. Group 3 (FBCF, 22-gauge cannula) had a mean bleb survival time of 19.2 ± 3.8 days. Group 4 (FBCF, 26-gauge cannula) had a mean bleb survival time of 19.7 ± 4.1 days. A 2-way analysis of variance showed that neither surgical approach nor cannula gauge made a statistically significant difference in bleb survival time (P = 0.634 and P = 0.874). Additionally, there was no significant interaction between cannula gauge and conjunctival flap approach (P = 0.874), suggesting that there was not a combination of drainage gauge and conjunctival flap method that produced superior bleb survival.

CONCLUSION

Limbus and fornix-based conjunctival flaps are equally effective in promoting bleb survival using both 22 and 26-gauge cannulas in the rabbit model. The 26-gauge drainage tube may be preferred because its smaller size facilitates the implantation process, reducing the risk of corneal contact.

Comparing glaucomatous disc change using stereo disc viewing and the MatchedFlicker programme in glaucoma experts and trainees

BACKGROUND/AIMS

The objective of this study is to evaluate the accuracy and speed of trainees and experienced glaucoma specialists using the MatchedFlicker software against the manual examination of stereoscopic disc photographs for detecting glaucomatous optic disc change.

METHODS

Three experienced glaucoma specialists, two resident ophthalmologists and one glaucoma fellow from multiple institutions independently evaluated the same 140 image pairs from 100 glaucomatous/ocular hypertensive eyes using a handheld stereo viewer and the MatchedFlicker programme. Fifty had progression to glaucoma as determined by the Ocular Hypertension Treatment Study (OHTS) Optic Disc Reading Group and endpoint committee, and 50 more were negative controls for progression with photos taken a few minutes apart. Twenty photo pairs from each of the two groups were duplicated for reviewer variability analysis. The initial viewing method was randomised and then alternated for each group of 70 image pairs. Reviewer accuracy and evaluation time for each method were measured.

RESULTS

Evaluators averaged 8.6 s faster per image pair (26%) with the MatchedFlicker programme than with the stereo viewer (p=0.0007). Evaluators correctly identified more image pairs when using the MatchedFlicker software over the stereo viewer (p=0.0003). There was no significant difference between the expert and trainee group in speed or overall accuracy for either method. Experts were significantly more consistent than trainees with the duplicate image pairs (p=0.029). Trainees appeared more reluctant to designate eyes as showing glaucoma progression than experts.

CONCLUSIONS

Both expert glaucoma specialists and ophthalmologists in various stages of training had greater accuracy and speed with the MatchedFlicker programme than with a handheld stereoscopic viewer.

Retrospective Comparison of Intermediate-term Efficacy of 350 mm2 Glaucoma Drainage Implants and Medium-sized 230-250 mm2 Implants

Aim

To compare the intermediate-term efficacy of a large surface area Baerveldt 350 mm² glaucoma drainage device (GDD) with medium surface area implants (Baerveldt 250 mm² and Molteno 3, 230, or 245 mm²).

Design

This is a retrospective, nonrandomized comparative trial.

Materials and methods

A total of 94 eyes of 94 patients of mixed glaucoma diagnoses without any prior glaucoma surgical procedures and who had undergone a glaucoma drainage implant surgery with either a large Baerveldt 350 mm² GDD or a medium-sized GDD (Baerveldt 250 mm² or Molteno 230 or 245 mm²) were reviewed for intraocular pressure (IOP), number of glaucoma medications, and visual acuity (VA) preoperatively, and at 1, 2, and 3 years postprocedure.

Results

No significant differences were found in mean IOP, number of glaucoma medications used, and VA at 1, 2, and 3 years postoperatively. The rate of additional glaucoma procedures was similar between the two groups.

Conclusion

There is no clear evidence that a larger implant surface area beyond 230 to 250 mm² is advantageous in providing intermediate-term IOP control.

Clinical significance

It may be technically easier to surgically place a GDD that does not need to have its wings placed underneath the recti muscles, and the IOP results are similar.

How to cite this article

Meyer AM, Rodgers CD, Zou B, Rosenberg NC, Webel AD, Sherwood MB. Retrospective Comparison of Intermediate-term Efficacy of 350 mm² Glaucoma Drainage Implants and Medium-sized 230-250 mm² Implants. J Curr Glaucoma Pract 2017;11(1):8-15.

Relationship between Glaucoma Drainage Device Size and Intraocular Pressure Control: Does Size Matter?

There is ambiguity in the literature regarding whether a larger glaucoma drainage device (GDD) achieves a lower long-term intraocular pressure (IOP). There is some evidence on both sides, but overall there seems to be an optimal surface area of approximately 200-250 mm² beyond which there may be little advantage to increasing the plate size for most patients.

HOW TO CITE THIS ARTICLE

Rodgers CD, Meyer AM, Sherwood MB. Relationship between Glaucoma Drainage Device Size and Intraocular Pressure Control: Does Size Matter? J Curr Glaucoma Pract 2017;11(1):1-2.

Porosity of Bleb Capsule declines rapidly with Fluid Challenge

Introduction

The porosity of the fibrous capsule around a glaucoma drainage device (GDD) may be the most important functional attribute. The factors that determine capsular porosity are not well understood. Failed GDD surgeries are usually associated with thick impervious capsules and components of aqueous have been implicated in this process.

Purpose

In this study, we interrogated the effect of passage of nonaqueous fluid on capsular porosity in mature (but aqueous naïve) blebs in a previously reported GDD model (the “Center for Eye Research Australia Implant”).

Materials and methods

The study was performed at two centers using 17 New Zealand White (NZW) rabbits. An experimental GDD was implanted into the subconjunctival space but without connection to the anterior chamber. After 28 days, balanced salt solution (BSS) was passed through the implant for 30 to 40 minutes at 12 mm Hg. Capsular porosity was measured as flow (μL/min) at a constant pressure. Porosity of the capsule was retested at 3 and 6 days.

Results

There was a marked reduction in capsular porosity within 3 days of exposure to BSS (fluid challenge). Even though the baseline porosity was significantly different in the two groups (3.00 ± 0.5 μL/min and 29.67 ± 12.12 μL/min, p < 0.001), the effect of passage of BSS was similar. Capsular porosity fell by approximately 80% in both groups from baseline after single BSS challenge. Capsular thickness was significantly less in Advanced Eye Center (AEC) rabbits at baseline. There was no change in the capsular thickness before and after single fluid challenge.

Conclusion

Passage of BSS at physiological pressures for under 40 minutes caused marked reduction in the porosity of the fibrous capsule within 3 days. This was not associated with any significant thickening of the fibrous capsule within this time frame.

How to cite this article

Pandav SS, Ross CM, Thattaruthody F, Nada R, Singh N, Gautam N, Beirne S, Wallace GG, Sherwood MB, Crowston JG, Coote M. Porosity of Bleb Capsule declines rapidly with Fluid Challenge. J Curr Glaucoma Pract 2016;10(3):91-96.

Comparing Glaucomatous Disc Change Using Stereo Disc Viewing and the MatchedFlicker Software Program in Ophthalmologists-in-Training

PURPOSE

To compare the accuracy and speed of using the computerized MatchedFlicker software program (EyeIC Inc, Narberth, Pennsylvania, USA) to evaluate glaucomatous optic disc change against the traditional gold standard of manually examining stereoscopic disc photographs.

DESIGN

A prospective evaluation of diagnostic technology.

METHODS

Two resident ophthalmologists and 1 glaucoma fellow at the University of Florida independently evaluated 140 image pairs from 100 glaucomatous/ocular hypertensive patient eyes using a handheld stereo viewer and the MatchedFlicker program. Fifty had progression to glaucoma as determined by the Ocular Hypertension Treatment Study (OHTS) Optic Disc Reading Group and the OHTS Endpoint Committee in the OHTS, and 50 more had photographs taken a few minutes apart, which were negative controls with no progression. Twenty photograph pairs from each group were duplicated to determine reviewer variability. Photographs were examined in alternating blocks of 70 photograph pairs for each method, with the starting viewing method randomized. Reviewer accuracy and time to review for each method were measured.

RESULTS

Using the handheld stereo viewer, the reviewers correctly identified progression or nonprogression in 76.0% of the slide pairs. Using the MatchedFlicker software, 87.6% were correctly identified (P = .011). Evaluator speed averaged 34.1 seconds per image pair with the stereo viewer vs 24.9 seconds with the MatchedFlicker program (P = .044). Overall, Flicker was significantly more specific but less sensitive than stereo slides. Trainees appeared more reluctant to identify glaucoma progression from slides than from Flicker. For the 2 less experienced trainees Flicker was significantly more accurate.

CONCLUSION

The MatchedFlicker software had a greater accuracy and was quicker to perform than using a handheld stereoscopic viewer.

Failed glaucoma drainage implant: long-term outcomes of a second glaucoma drainage device versus cyclophotocoagulation

BACKGROUND/AIMS

To evaluate long-term efficacy of a second glaucoma drainage device (GDD) versus cyclophotocoagulation (CPC) after failure of primary drainage implant.

METHODS

This is a non-randomised, retrospective cohort study. A chart review was conducted of patients who underwent GDD surgery between July 1986 and November 2012 requiring further glaucoma procedures for intraocular pressure (IOP) control. An additional GDD was placed in 15 eyes, while 32 eyes underwent CPC. The main outcome measurement was IOP control and/or time to failure of secondary intervention (IOP >18 mm Hg on two sequential measurements).

RESULTS

Mean follow-up after the second procedure was 63±65.8 months (range 6-254 months) in the CPC group and 132±91.8 months (range 12-254 months) in the GDD group. Thirty-four per cent (11/32 eyes) undergoing CPC later required further treatment at a mean of 13.6±10.7 months with 10/11(91%) of additional interventions occurring within 2 years. Despite an initially high success rate for IOP control in the first 5 years, eventually 60% (9/15 eyes) that underwent a second tube required additional treatment at a mean of 73.4 months with only 2/9(22%) requiring this within the first 2 years. The risk of visual acuity worsening by 2 Snellen lines or more at 12 months was 5/14 for the GDD group (36%) and 4/23(17%) for the CPC group.

CONCLUSIONS

After failure of an initial drainage implant to control IOP, a sequential tube had a high initial rate of success but a relatively high likelihood of long-term failure, generally after 6 years. Eyes that received CPC tended to fail earlier, often within the first year, but had relatively few late failures.

Randomized, prospective, comparative trial of EX-PRESS glaucoma filtration device versus trabeculectomy (XVT study)

PURPOSE

To compare the clinical outcomes of the EX-PRESS glaucoma filtration device placed under a partial-thickness scleral flap with trabeculectomy.

DESIGN

Randomized, prospective, multicenter trial.

METHODS

A total of 120 eyes in 120 subjects were analyzed, including 59 eyes treated with EX-PRESS and 61 eyes treated with trabeculectomy. Both the EX-PRESS and the trabeculectomy groups were treated intraoperatively with mitomycin C and followed postoperatively for 2 years. Surgical success was defined as 5 mm Hg ≤ intraocular pressure ≤ 18 mm Hg, with or without medications, without further glaucoma surgery.

RESULTS

Mean intraocular pressure was significantly reduced compared with baseline in both groups (P < 0.001). Average intraocular pressure and number of medications were similar in both groups during follow-up, with mean intraocular pressure at 2 years after surgery of 14.7 ± 4.6 mm Hg and 14.6 ± 7.1 mm Hg in the EX-PRESS and trabeculectomy groups, respectively (P = 0.927). At 2 years after surgery, the success rate was 83% and 79% in the EX-PRESS and trabeculectomy groups, respectively (P = 0.563). Although visual acuity (logMAR) was significantly decreased on day 1 in both groups, the vision was not significantly different compared with baseline at 1 month after EX-PRESS implant (P = 0.285) and 3 months after trabeculectomy (P = 0.255). The variance of early postoperative intraocular pressure values was similar between groups on the first postoperative day but higher after trabeculectomy compared with EX-PRESS implant on day 7 (P = 0.003). The total number of postoperative complications was higher after trabeculectomy than after EX-PRESS implantation (P = 0.013).

CONCLUSIONS

Mean intraocular pressures, medication use, and surgical success were similar at 2 years after treatment with the EX-PRESS device and trabeculectomy. Vision recovery between groups was also similar throughout the study, although return to baseline vision was more rapid in the EX-PRESS group. Intraocular pressure variation was lower during the early postoperative period, and postoperative complications were less common after EX-PRESS implantation compared with trabeculectomy.

Preclinical potency and safety studies of an AAV2-mediated gene therapy vector for the treatment of MERTK associated retinitis pigmentosa

Abstract Proof of concept for MERTK gene replacement therapy has been demonstrated using different viral vectors in the Royal College of Surgeon (RCS) rat, a well characterized model of recessive retinitis pigmentosa that contains a mutation in the Mertk gene. MERTK plays a key role in renewal of photoreceptor outer segments (OS) by phagocytosis of shed OS tips. Mutations in MERTK cause impaired phagocytic activity and accumulation of OS debris in the interphotoreceptor space that ultimately leads to photoreceptor cell death. In the present study, we conducted a series of preclinical potency and GLP-compliant safety evaluations of an adeno-associated virus type 2 (AAV2) vector expressing human MERTK cDNA driven by the retinal pigment epithelium-specific, VMD2 promoter. We demonstrate the potency of the vector in RCS rats by improved electroretinogram (ERG) responses in treated eyes compared with contralateral untreated controls. Toxicology and biodistribution studies were performed in Sprague-Dawley (SD) rats injected with two different doses of AAV vectors and buffer control. Delivery of vector in SD rats did not result in a change in ERG amplitudes of rod and cone responses relative to balanced salt solution control-injected eyes, indicating that administration of AAV vector did not adversely affect normal retinal function. In vivo fundoscopic analysis and postmortem retinal morphology of the vector-injected eyes were normal compared with controls. Evaluation of blood smears showed the lack of transformed cells in the treated eyes. All injected eyes and day 1 blood samples were positive for vector genomes, and all peripheral tissues were negative. Our results demonstrate the potency and safety of the AAV2-VMD2-hMERTK vector in animal models tested. A GMP vector has been manufactured and is presently in clinical trial.

Wound modulation after filtration surgery

Filtration surgery is the standard invasive procedure for the management of intraocular pressure in advanced glaucoma. The key to a successful outcome is to modulate the normal wound healing cascade that leads to closure of the newly created aqueous outflow pathway. Antifibrotic agents such as mitomycin C and 5-fluorouracil have been increasingly used to modulate the wound healing process and increase surgical success. Although these agents have proven efficacy, they also increase the risk of complications. Efforts have centered on the identification of novel agents and techniques that can influence wound modulation without these complications. We detail new agents and methods under investigation to control wound healing after filtration surgery.

Comparison of single versus multiple injections of the protein saratin for prolonging bleb survival in a rabbit model

PURPOSE

We compared the anti-fibrotic effects of single versus multiple postoperative injections of saratin following glaucoma filtration surgery (GFS) in the rabbit model.

METHODS

The experiment was in two parts. To determine the optimal frequency for postoperative therapy, seven New Zealand White (NZW) rabbits received an injection of saratin under the superior conjunctiva bilaterally, and ocular tissue concentration was determined using Western blot and bicinchoninic acid (BCA) assay. Next, 32 additional NZW rabbits underwent filtration surgery and received either single or multiple-dose saratin treatments. Mitomycin-C (MMC) and balanced saline solution (BSS) treatment acted as positive and negative controls, respectively.

RESULTS

Rabbits receiving only one perioperative saratin injection had a mean bleb survival time of 29.8 ± 5.3 days, while those receiving multiple (either 3 or 5+) injections of saratin had mean bleb survival times of 26.3 ± 8.1 and 26.4 ± 4.2 days, respectively. Analysis of variance with post-hoc testing showed the single injection group had a statistically favorable effect on bleb survival duration compared to BSS controls and was not significantly different from MMC. The conjunctivas of the saratin-treated rabbits did not show the thinning or avascularity that was seen in the MMC treatment group. Rabbits receiving more than three injections of saratin suffered temporary conjunctival redness and two rabbits had upper eyelid edema.

CONCLUSIONS

A single postoperative injection of saratin was able to prolong the duration of bleb elevation when compared to BSS controls. Additional treatments of saratin seemed to reduce effectiveness and caused short-term eye inflammation.

Prevention of ocular scarring post glaucoma filtration surgery using the inflammatory cell and platelet binding modulator saratin in a rabbit model

Clinical Relevance

Late complications can occur with use of current antimetabolites to prevent scarring following glaucoma filtration surgery (GFS). Safer, more targeted, anti-fibrosis agents are sought.

Objectives

The protein saratin has been shown to exhibit anti-fibrotic and anti-thrombotic properties in response to injury, but had not been used for glaucoma surgery. The goal of this study was to compare the efficacy of saratin with that of the widely accepted mitomycin-C (MMC) in prolonging bleb survival following GFS in the rabbit model. Two saratin delivery routes were compared; a single intraoperative topical application versus a combination of intraoperative topical application with two additional postoperative injections.

Methods

Twenty-four New Zealand White rabbits underwent GFS and received either intraoperative topical saratin, intraoperative topical saratin plus two injections on post-operative days 4 and 8, balanced saline solution (BSS), or MMC. The bleb tissues and their elevation durations were compared based on clinical and histological findings.

Results

Rabbits receiving topical+injections of saratin had a mean bleb survival of 33.6±8.5 days, significantly higher than the negative BSS controls, which averaged 17.4±6.0 days (p = 0.018). No improvement over BSS was seen for rabbits receiving topical saratin only (15.5±4.8 days, p = 0.749). Rabbits receiving saratin did not develop bleb avascularity and thinning associated with MMC treatment and there were no apparent clinical signs of toxicity.

Conclusions

Treatment with a single intraoperative topical application plus two additional postoperative injections significantly prolonged bleb elevation comparable to MMC, but without toxicity; however, topical application alone was ineffective.

Ab-externo AAV-mediated gene delivery to the suprachoroidal space using a 250 micron flexible microcatheter

Background

The current method of delivering gene replacement to the posterior segment of the eye involves a three-port pars plana vitrectomy followed by injection of the agent through a 37-gauge cannula, which is potentially wrought with retinal complications. In this paper we investigate the safety and efficacy of delivering adeno-associated viral (AAV) vector to the suprachoroidal space using an ab externo approach that utilizes an illuminated microcatheter.

Methods

6 New Zealand White rabbits and 2 Dutch Belted rabbits were used to evaluate the ab externo delivery method. sc-AAV5-smCBA-hGFP vector was delivered into the suprachoroidal space using an illuminated iTrackTM 250A microcatheter. Six weeks after surgery, the rabbits were sacrificed and their eyes evaluated for AAV transfection using immunofluorescent antibody staining of GFP.

Results

Immunostaining of sectioned and whole-mounted eyes demonstrated robust transfection in all treated eyes, with no fluorescence in untreated control eyes. Transfection occurred diffusely and involved both the choroid and the retina. No apparent adverse effects caused by either the viral vector or the procedure itself could be seen either clinically or histologically.

Conclusions

The ab externo method of delivery using a microcatheter was successful in safely and effectively delivering a gene therapy agent to the suprachoroidal space. This method presents a less invasive alternative to the current method of virally vectored gene delivery.

Twice-Daily 0.2% Brimonidine–0.5% Timolol Fixed-Combination Therapy vs Monotherapy With Timolol or Brimonidine in Patients With Glaucoma or Ocular Hypertension

OBJECTIVE

To evaluate the intraocular pressure (IOP)-lowering efficacy and safety of a fixed combination of 0.2% brimonidine tartrate and 0.5% timolol maleate (fixed brimonidine-timolol) compared with the component medications.

METHODS

In 2 identical, 12-month, randomized, double-masked multicenter trials, patients with ocular hypertension or glaucoma were treated with fixed brimonidine-timolol twice daily (n = 385), 0.2% brimonidine tartrate 3 times daily (n = 382), or 0.5% timolol maleate twice daily (n = 392).

MAIN OUTCOMES MEASURES

Mean change from baseline IOP and incidence of adverse events.

RESULTS

The mean decrease from baseline IOP during 12-month follow-up was 4.4 to 7.6 mm Hg with fixed brimonidine-timolol, 2.7 to 5.5 mm Hg with brimonidine, and 3.9 to 6.2 mm Hg with timolol. Mean IOP reductions were significantly greater with fixed brimonidine-timolol compared with timolol at all measurements (P< or =.002) and brimonidine at 8 am, 10 am, and 3 pm (P<.001) but not at 5 pm. The incidence of treatment-related adverse events in the fixed-combination group was lower than that in the brimonidine group (P = .006) but higher than that in the timolol group (P<.001). The rate of discontinuation for adverse events was 14.3% with the fixed combination, 30.6% with brimonidine, and 5.1% with timolol.

CONCLUSIONS

Twice-daily fixed brimonidine-timolol therapy provides sustained IOP lowering superior to monotherapy with either thrice-daily brimonidine or twice-daily timolol and is better tolerated than brimonidine but less well tolerated than timolol.

APPLICATION TO CLINICAL PRACTICE

Fixed brimonidine-timolol is an effective and convenient IOP-lowering therapy.

Microarray analysis of the failure of filtering blebs in a rat model of glaucoma filtering surgery

PURPOSE

To generate data concerning changes in levels of protein expression associated with wound healing and bleb failure in a rat model of glaucoma filtration surgery (GFS), and to identify factors that may play a role in this process.

METHODS

Of 36 Sprague-Dawley rats, GFS was performed on 27 by introducing a silicone cannula through a scleral tunnel under a conjunctival flap, resulting in aqueous-filtering blebs that failed over 8 to 13 days. The additional nine rats were used as the nonsurgical control. Nine blebs were harvested at each of days 0, 2, 5, and 12 and pooled, yielding three replicates of three blebs per time point. RNA was extracted, labeled, and hybridized to 230A rat GeneChip arrays (Affymetrix, Santa Clara, CA).

RESULTS

Of the 15,924 probe sets/genes present on the array, 923 genes were indicated to have a significant treatment effect at P < 0.005. Eight gene expression clusters were identified that could be broadly classified into three basic patterns. These were an increase on day 2, a decrease on day 2, or an increase on either day 5 or 12. The greatest change occurred between days 0 and 2. The most heavily populated functional categories included growth factors, structural proteins, and matrix metalloproteinases.

CONCLUSIONS

This study represents the first large-scale gene expression analysis after GFS. Expression patterns for known mediators of the bleb scarring process, including transforming growth factor-beta, connective tissue growth factor, and matrix metalloproteinases, were confirmed, and a number of mediators not previously associated with this process were identified.

A New Model of Glaucoma Filtering Surgery in the Rat

PURPOSE

The most common reason for long-term failure of glaucoma filtering surgery (GFS) is scarring of the external filtering "bleb" tissues. The identification of the factors that mediate this process, as well as the development and initial testing of new therapies to limit scarring is enhanced by the use of appropriate animal models. The standard animal model for studying GFS is the rabbit but newer investigative tools that examine changes induced in biologic systems at a genetic level have made development of a rat model desirable.

METHODS

Glaucoma filtering surgery was performed on 20 Sprague-Dawley rats by introducing a 30-gauge silicone cannula through a penetrating scleral tunnel, under a limbal-based conjunctival flap and suturing the conjunctiva closed. Identical GFS was performed on 3 additional rats, which underwent histologic evaluation at days 2, 5, and 11, following surgery.Fistulizing surgery was also performed on 6 Sprague-Dawley rats, for comparison, by creating a full-thickness needle sclerostomy under a limbal-based conjunctival flap and suturing the conjunctiva closed.

RESULTS

Following the cannula GFS, well-elevated filtering blebs formed and these gradually failed over the course of 8 to 13 days. Needle tract sclerostomy filtering blebs formed at the site of the fistulizing surgery but rapidly failed over the course of 2 to 3 days.

CONCLUSION

Cannulated filtering surgery in the rat provides a longer lasting and more predictable model than needle tract sclerostomy for studying wound healing following GFS and may facilitate the study of induced changes at the gene level.

Functional and Structural Analysis of the Visual System in the Rhesus Monkey Model of Optic Nerve Head Ischemia

PURPOSE

A redistribution of neurochemicals has been identified in the visual cortex of monkeys with laser-induced glaucoma. Examined were functional, structural, and neurochemical changes to the retina, optic nerve, and central visual system in a nonhuman primate model of optic nerve head (ONH) ischemia caused by sustained unilateral administration of endothelin (ET)-1 to the optic nerve.

METHOD

ET-1 or sham control solution was delivered by osmotic minipump to the retrolaminar region of one optic nerve of rhesus monkeys (Macaca mulatta) for 1.5 years. ONH topography and blood flow velocity were serially studied with scanning laser tomography and laser Doppler flowmetry, respectively. Retinal and cortical electrophysiologic measurements from pattern-derived stimuli were obtained quarterly. Immunohistochemistry was used to identify the distribution of calbindin (CB) and c-Fos labeled neurons in the visual cortex areas V1 and V2, and lateral geniculate nucleus (LGN). Retinal ganglion cell counts and optic nerve axon density were determined by light microscopy.

RESULTS

No significant changes in retinal and ONH morphology, ONH blood flow velocity, and retinal and cortical pattern-derived functional activity were detected. Measurement of CB-positive cell density in V1 and V2 showed a significant decrease in CB labeling to the contralateral side of the ET-1-treated eye (P < 0.04). CB-positive cells were present in the magnocellular layers of the LGN with no differences noticed between the ET-1- and sham-treated eyes. c-Fos-labeled neurons were found in striate area V1 and extrastriateV2 of both groups. No c-Fos labeling was observed in the LGN.

CONCLUSIONS

Administering ET-1 to the orbital optic nerve alters neuronal metabolic activity in the visual cortex in rhesus monkeys. Metabolic activity reductions in the visual cortex precede the ability to detect functional and structural alterations in the retina, ONH, and visual cortex in this animal model.

Is Addition of a Third or Fourth Antiglaucoma Medication Effective?

PURPOSE

To study the intraocular pressure (IOP)-lowering effect of adding a third or a fourth antiglaucoma medication to preexisting antiglaucoma medical therapy, for a follow-up period of one year.

PATIENTS AND METHODS

The authors performed a retrospective, nonrandomized, noncomparative, interventional study including all patients seen by a single glaucoma specialist at the University of Florida Eye Clinic between January 1, 2000 and December 31, 2000, who had a third or a fourth antiglaucoma medication added to their existing regimen of two or three antiglaucoma medications, respectively. The main outcome measured was IOP at 2, 6, 9, and 12 months after addition of an antiglaucoma medication. "Efficacy" success was defined as a decrease in intraocular pressure of greater than or equal to 20% from baseline, without a change in the antiglaucoma medical therapy. Also, "safety outcome" was analyzed based on the need for surgical intervention and/or the occurrence of intolerable side effects to the antiglaucoma medications leading to discontinuation of their use.

RESULTS

Sixty-seven patients had a third, and 29 patients had a fourth antiglaucoma medication added to their existing regimen. Analysis for a specific time point showed a success rate of 48% at 2 months (n = 65), 47% at 6 months (n = 47), and 41% at 1 year (n = 39) after addition of a third antiglaucoma medication and 59% at 2 months (n = 29), 45% at 6 months (n = 22), and 55% at 1 year (n = 20) after addition of a fourth antiglaucoma medication. By Kaplan-Meier analysis the cumulative probability of achieving efficacy success (> or = 20% IOP decrease from baseline) was 33% at 6 months and 23% at 1 year after adding a third medication (Group A), and 43% at 6 months and 18% at 1 year after adding a fourth medication (Group B). Combining both efficacy and safety outcomes decreased the cumulative probability of success to 27% and 14% in Group A, and 31% and 14% for Group B, at 6 months and 1 year respectively.

CONCLUSION

Addition of a third and fourth antiglaucoma medication produces a clinically significant reduction in IOP in about 40 to 60% of patients at any single time point. However, the cumulative probability of success including safety outcomes is relatively poor at 6 months and 1 year. This suggests that adding another antiglaucoma medication to a regimen of two or three medications frequently does not achieve a significant (> or = 20%) fall in IOP.

Time-specific intraocular pressure curves in Rhesus macaques (Macaca mulatta) with laser-induced ocular hypertension

OBJECTIVE

To detect and categorize time-specific variations in daytime intraocular pressure (IOP) found in Rhesus monkeys with laser-induced ocular hypertension.

PROCEDURES

Ten male monkeys with argon laser-induced ocular hypertension in one eye were anesthetized with ketamine hydrochloride, and the IOP measured in both eyes at 7 a.m., 7.30 a.m., and then hourly until 1 p.m. with a Tonopen trade mark XL applanation tonometer. Intraocular pressure time profiles for both eyes in each animal were developed. The means +/- SD of the IOPs for both eyes were calculated for the whole 6-h study period, and the values compared statistically. The difference between the lasered eye mean IOP standard deviation and the normal eye mean IOP standard deviation for each animal during the 6-h follow-up was also calculated and compared.

RESULTS

Mean IOP (+/- SD) in the glaucoma and normal eyes for the 10 animals during the 6-h study was 32.6 +/- 2.5 and 14.9 +/- 2.5 mmHg, respectively. The IOP was significantly higher in the experimental eye than in the normal eye (P = 0.0008). The mean IOP in the lasered eye did not significantly change during the study period, whereas a slight but significant increase in IOP of the normal eye over the study period was recorded (P = 0.003). The variance in IOP in the hypertensive eyes was considerably greater than that in the untreated control eyes. From 7 a.m. to 1 p.m. the IOP declined in five eyes and increased in the other five eyes with laser-induced ocular hypertension.

CONCLUSIONS

The time-specific IOP variation pattern in the daytime in the laser treated eyes is significantly greater than the variation in the normotensive eyes. This shows that in order to detect statistical differences between IOP variations induced by an IOP-reducing drug, and the exaggerated spontaneous IOP variations present in the laser-induced hypertensive eye, sufficient animals should be included in any study. Understanding the time-specific IOP variation present in a group of monkeys with laser-induced ocular hypertension is essential prior to using the model for the evaluation of IOP-reducing drugs.

Expression of Connective Tissue Growth Factor after Glaucoma Filtration Surgery in a Rabbit Model

PURPOSE

Connective tissue growth factor (CTGF) appears to play a significant role in mediating fibrosis in several tissues. To gain further understanding of the role of CTGF in the scar formation that occurs after glaucoma filtering surgery (GFS), experiments were performed in a rabbit model.

METHODS

. Three experiments were performed: (1) CTGF and transforming growth factor (TGF)-beta expression were measured quantitatively after GFS, using ELISA. (2) After GFS conjunctival bleb tissues were immunostained for the presence of CTGF and TGF-beta. (3) Exogenous CTGF was injected into mitomycin-C (MMC)-treated filtering blebs and the scaring response compared to TGF-beta and physiological saline-injected blebs.

RESULTS

CTGF and TGF-beta were expressed maximally by day 5 after surgery and were both shown to be present in the bleb tissues after GFS. The addition of exogenous CTGF and TGF-beta increased the rate of failure of GFS blebs.

CONCLUSIONS

These data support the hypothesis that CTGF plays an important role in scarring and wound contracture after GFS. Inhibition of CTGF synthesis or its action may help prevent bleb failure and improve long-term GFS outcomes.

Long-term effect of retinal ganglion cell axotomy on the histomorphometry of other cells in the porcine retina

PURPOSE

To determine the effect of retinal ganglion cell axotomy on the thickness of inner plexiform, inner nuclear, and outer plexiform layers, as well as the densities of short- and middle-to-long-wavelength cones, in the porcine retina.

METHODS

Unilateral retinal ganglion cell axotomy was performed in seven domestic pigs by either surgical optic nerve section or peripapillary argon laser photocoagulation. Damage to the retinal vasculature was ruled out with fluorescein angiography. Histologic examination of the retinal tissue was performed nine months later. Cone densities were determined immunohistochemically with the anti-visual pigment antibodies COS-1 and OS-2. Image analysis of semithin retinal cross sections was used to measure the thickness of the retinal layers. The effect of axotomy was quantified by optic nerve axon counts and estimations of retinal ganglion cell counts. The data were compared between the eyes with axotomy and the contralateral normal eye using the nonparametric Wilcoxon rank sum test.

RESULTS

Treatment of the peripapillary retina with the argon laser resulted in a median decrease in axon counts and retinal ganglion cell density estimates of 31%. No optic nerve axons and cells resembling retinal ganglion cells were found in the eyes with transected optic nerves. There was no significant difference in either the thickness of any retinal layers or cone densities between axotomized and normal control eyes.

CONCLUSION

No signs of retrograde transsynaptic degeneration were observed in porcine retinas nine months after retinal ganglion cell axotomy.

Corneal thickness and endothelial cell density measured by non-contact specular microscopy and pachymetry in Rhesus macaques (Macaca mulatta) with laser-induced ocular hypertension

PURPOSE

Sustained increase in intraocular pressure (IOP) in humans results in a loss of corneal endothelial cells and an increase of corneal thickness. The effects of chronically elevated IOP on the corneal endothelium of monkeys with laser-induced ocular hypertension, a commonly used animal model of human glaucoma have not been documented. This study examined the central corneal thickness (CCT), the corneal endothelial cell density (ECD), and the corneal endothelial cell size (ACS) in Rhesus monkeys with experimental ocular hypertension. Materials and methods. Ten male monkeys with argon laser-induced ocular hypertension in one eye for an average duration of 2.4+/-0.7 years, were sedated with ketamine hydrochloride, and the CCT, ECD, and ACS measured at the center of the cornea of both eyes with a Topcon SP-2000P non-contact specular microscope (Topcon America Corporation((R)), Paramus, NJ, USA). CCT was also measured using a DHG-500 Pachette ultrasonic pachymeter (DHG Technology Inc., Exton, PA, USA). Mean and standard deviation (S.D.) of CCT, ECD and ACS for each eye was calculated and statistically compared.Results. Mean CCT in the hypertensive and normal eyes measured by specular microscopy was 0.477+/-0.023mm and 0.468+/-0.020 mm, respectively. Mean ECD in the hypertensive and normal eyes was 2601.7+/-631.8 and 3990.2+/-402.9 cells mm(-2), respectively. The mean size of the endothelial cells was 252.4+/-23.9 micro m(2) in the normal eye and 408.7+/-115.0 microm m(2) in the hypertensive eye. No significant difference in the measurement of CCT was observed between the specular microscope and the pachymeter (p=0.46). No significant difference in the mean CCT was observed between the two eyes (p=0.4820), whereas the mean ECD was significantly lower in the hypertensive eye than in the normal eye (p<0.001). The ECD was inversely related to the length of IOP elevation (p<0.001).

CONCLUSIONS

No difference in the corneal thickness measurement was observed between the specular microscopy and the pachymetry techniques. Chronic ocular hypertension did not significantly affect the CCT, but caused a significant loss of endothelial cells in the center of the cornea of the laser treated eyes compared to the normotensive eyes. The duration of elevated IOP was the most important factor affecting the ECD.

Passive attenuation of cortical pattern evoked potentials with increasing body weight in young male rhesus macaques

The purpose of our study was to determine changes in amplitudes and implicit times of retinal and cortical pattern evoked potentials with increasing body weight in young, growing rhesus macaques (Macaca mulatta). Retinal and cortical pattern evoked potentials were recorded from 29 male rhesus macaques between 3 and 7 years of age. Thirteen animals were reexamined after 11 months. Computed tomography (CT) was performed on two animals to measure the distance between the location of the skin electrode and the surface of the striate cortex. Spearman correlation coefficients were calculated to describe the relationship between body weights and either root mean square (rms) amplitudes or implicit times. For 13 animals rms amplitudes and implicit times were compared with the Wilcoxon matched pairs signed rank test for recordings taken 11 months apart. Highly significant correlations between increases in body weights and decreases in cortical rms amplitudes were noted in 29 monkeys (p < 0.0005). No significant changes were found in the cortical rms amplitudes in thirteen monkeys over 11 months. Computed tomography showed a large increase of soft tissue thickness over the skull and striate cortex with increased body weight. The decreased amplitude in cortical evoked potentials with weight gain associated with aging can be explained by the increased distance between skin electrode and striate cortex due to soft tissue thickening (passive attenuation).

Enhanced short-term plasmid transfection of filtration surgery tissues

PURPOSE

To quantify and localize plasmid transfection of filtration surgery tissues using two delivery techniques.

METHODS

Full-thickness filtering procedures were performed on eyes of New Zealand albino rabbits. In 10 eyes, naked plasmid DNA in saline was either injected beneath Tenon's capsule at the filtration site or absorbed into a collagen shield that was then placed external to the sclerostomy and under the Tenon's capsule. Forty-eight hours after surgery, levels of the reporter gene, chloramphenicol acetyltransferase (CAT) were measured in samples of ocular tissues. In two additional eyes, the ss-galactosidase (ss-GAL:) reporter gene expression was localized histologically.

RESULTS

Injection of plasmid DNA in saline vehicle into the filtration bleb produced readily detectable CAT activity in bleb tissue (conjunctiva, Tenon's capsule, and sclera) whereas CAT activity was nearly undetectable in samples of the cornea, iris-ciliary body, and tissues located opposite the bleb site. Delivery of the plasmid DNA into the bleb through a collagen shield increased CAT activity 30-fold over injection of plasmid in saline (2711 +/- 567 mU/mg versus 92 +/- 38 mU/mg). ss-Gal activity was imaged only in the region of the bleb, and microscopic examination showed ss-Gal activity localized to Tenon's capsule fibroblasts, with minimal ss-Gal activity observed in inflammatory cells or scleral fibroblasts.

CONCLUSIONS

Transfection of filtration tissues is enhanced by absorption of naked DNA into a collagen shield. Furthermore, transfection is localized to the fibroblasts and inflammatory cells of the filtration bleb site. Gene therapy using naked plasmid DNA and a simple collagen shield delivery vehicle may be useful for regulating wound healing after glaucoma surgery.

A randomized trial of the effect of midazolam on intraocular pressure

PURPOSE

The effect of midazolam on intraocular pressure (IOP) in adults was studied as an initial step in determining whether it can be used as a preoperative anxiolytic or sedative agent in children with glaucoma who are undergoing examination for IOP measurements.

METHODS

This study followed a prospective, placebo controlled, randomized, double masked design. Fifty-five participants were enrolled after informed consent was obtained. Each enrolled patient underwent a brief history and eye examination. Measurements of IOP were taken at baseline and 5, 10, and 15 minutes after intravenous administration of 1 mg midazolam or placebo. IOP was the primary outcome measured.

RESULTS

There was no difference in IOP fluctuation from baseline between patients who received midazolam and those who received placebo.

CONCLUSION

Early results indicate that because midazolam does not lower IOP, it may be a useful adjunct to ketamine anesthesia in children with glaucoma undergoing ophthalmologic examination under anesthesia. However, studies of midazolam must be conducted in children and patients with glaucoma before its use in these populations can be recommended.

Mid-peripheral pattern electrical retinal responses in normals, glaucoma suspects, and glaucoma patients

AIMS

Reliance on intraocular pressure, optic nerve cupping changes, nerve fibre layer integrity, and visual field changes may delay treatment of glaucoma since irreversible changes may have already occurred at the time of diagnosis. Abnormal pattern electrical retinal responses (PERR or PERG) have been demonstrated in patients with ocular hypertension (no visual field changes) and glaucoma when visual stimulation was presented to the central field. Since glaucomatous visual field changes tend to occur first in the mid-periphery, the use of PERR outside of the central field may offer an earlier indication of glaucomatous involvement.

METHODS

Glaucoma suspects and glaucoma patients were derived from a university practice. Normal subjects were recruited from non-patient volunteers. Alternating bar gratings were presented in the supranasal, supratemporal, infratemporal, and infranasal visual field. Six spatial frequencies, from 0.25 to 6.0 cycles per degree, were used for normal volunteers; three spatial frequencies, from 0.38 to 1.5 cycles per degree, were presented to suspects and glaucoma patients. Time of onset of the first negative (N35) and first positive peak (P50) and the amplitude consisting of the absolute difference between the first negative peak and first positive peak (P50 amplitude) are reported. Age corrected values were determined for normals, suspects, and glaucoma patients for each spatial frequency and for each quadrant in the visual field.

RESULTS

Mean P50 amplitudes from normal subjects showed spatial tuning in all quadrants with reduced low frequency attenuation. Normals demonstrated a small decline in amplitude with age. Glaucoma patients demonstrated an age corrected reduction in amplitude and early implicit times. Glaucoma suspects had values between those of normal and glaucoma subjects. P50 amplitudes were weakly correlated with increasing cup to disc diameter ratio. A glaucoma patient with asymmetric visual field loss demonstrated significant diminution of the PERR bilaterally.

CONCLUSION

The PERR, using mid-peripheral stimulation, may be a sensitive tool for the early detection of glaucoma. Further refinements can speed clinical data acquisition and enhance signal to noise ratio.

Signs of glaucoma in rhesus monkeys from a restricted gene pool

PURPOSE

To investigate the distribution of intraocular pressure (IOP) and cup properties in a colony of rhesus monkeys that has had no outside genetic input since 1938 (approximately 12 generations). This sample of sequestered monkeys is significantly larger than any previously reported. Comparisons are made with a sample of random-source monkeys to develop population estimates defining the limits of normalcy.

METHODS

The IOP and cup/disc ratio estimates were collected from 701 eyes of 354 adult rhesus monkeys from the closed colony on Cayo Santiago, Puerto Rico. Results for IOP were compared with the normal rhesus IOP population distribution function calculated from an earlier sample of genetically heterogeneous rhesus.

RESULTS

The mean +/- standard deviation IOP in the Cayo Santiago monkeys (15.8+/-3 mmHg) related well to the calculated "normal" rhesus distribution (14.5+/-2 mmHg) below and around the mean IOP only. Above the mean rhesus IOP, the samples from the Cayo monkeys were strongly skewed: 129 eyes had IOP more than two standard deviations above the normal mean IOP, and 54 eyes had IOP more than three standard deviations above the normal mean IOP. Cup/disc ratio estimations tended to cluster as higher values in the higher IOP quartiles. Some eyes with IOP below the mean had cup/disc ratios > 0.5. Values for IOP that were more than two standard deviations above the mean and cup/disc ratios > 0.4 were not uniformly distributed across social groupings, although incidence of high IOP was more than 25% in one group.

CONCLUSION

After 12 generations with the same genetic pool, expression of ocular hypertension and large optic disc cups is high but not uniform.

Change in intraocular pressure during long-term use of loteprednol etabonate

PURPOSE

Loteprednol etabonate is a novel site-active corticosteroid synthesized through structural modifications of prednisolone-related compounds so that it will undergo a predictable transformation to an inactive metabolite. In double-masked studies, loteprednol etabonate was effective in the treatment of giant papillary conjunctivitis, seasonal allergic conjunctivitis, postoperative inflammation, and uveitis. The objective of this analysis was to determine the incidence of clinically significant elevations in intraocular pressure (IOP) with long-term use of loteprednol etabonate.

PATIENTS AND METHODS

All subjects (healthy volunteers or patients with inflammation or allergy) in all sponsored loteprednol etabonate studies in the United States were evaluated. A clinically significant elevation in IOP was defined as > or = 10 mmHg at any visit, and long-term use was defined as > or = 28 days. Of the 2,210 subjects, 1,648 were treated for 28 days or longer with loteprednol etabonate (0.2% or 0.5%), prednisolone acetate 1%, or vehicle.

RESULTS

IOP elevation > or = 10 mmHg occurred in 1.7% (15/901) of patients taking long-term loteprednol etabonate, 0.5% (3/583) of those taking vehicle, and 6.7% (11/164) of those taking prednisolone acetate. Excluding patients who wore contact lenses, the incidence was 0.6% (4/624), 1.0% (3/304), and 6.7% (11/164) for loteprednol etabonate, vehicle, and prednisolone acetate, respectively. The incidence of IOP elevations with 0.2% loteprednol etabonate was 0.8% (1/133), similar to that for vehicle (0.7%, 1/135).

CONCLUSION

The results of this analysis in a large population of subjects undergoing long-term therapy and of a previously published controlled, double-masked study in corticosteroid responders suggest that loteprednol etabonate has less propensity to cause clinically significant elevations in IOP than prednisolone acetate.

Diurnal intraocular pressure curves in healthy rhesus macaques (Macaca mulatta) and rhesus macaques with normotensive and hypertensive primary open-angle glaucoma

PURPOSE

The authors identify any diurnal intraocular pressure (IOP) variation in healthy Cayo Santiago macaques, as well as Cayo Santiago macaques with normotensive and hypertensive primary open-angle glaucoma (POAG), to further evaluate their potential value as a model for human POAG.

METHODS

Twenty-four monkeys (eight animals each of the healthy control, normotensive glaucoma, and hypertensive glaucoma groups) were sedated with ketamine hydrochloride and the IOP measured hourly from 8:00 AM until 3:00 PM with a Tonopen XL applanation tonometer (Mentor, Norwell, MA, U.S.A.). Mean IOP time profiles, mean IOPs at each observation time, and linear trends in mean IOP over time were compared among groups. Intraocular pressure rate-of-change over time and residual variation about the regression line for each individual eye were analyzed. Cup/disc ratio (C/D) was compared with baseline IOP, IOP profile mean and slope, and IOP residual variation.

RESULTS

A significant group and time effect on mean IOP (p = 0.0001 and 0.011, respectively), with highest values at 2:00 PM or 3:00 PM, and a significant increasing linear trend in mean IOP over time in the hypertensive group were observed (p = 0.012). Intermediate readings between control and hypertensive mean IOPs were identified for the normotensive glaucoma group. The biggest range of IOP variation was found in the hypertensive glaucoma monkeys. Higher variations in IOP did not lead to an increase in C/D.

CONCLUSIONS

This study provides evidence that the Cayo Santiago macaques are a valuable model for human normotensive and hypertensive POAG.

Glaucoma's impact on quality of life and its relation to clinical indicators. A pilot study

OBJECTIVE

This study aimed to compare the quality of life (Q of L) of patients with glaucoma and control subjects and to determine the relationships between Q of L and demographic and clinical variables in patients with glaucoma.

DESIGN

The study design was a stratified cross-sectional study.

PARTICIPANTS

A gender-, race-, and age-stratified cross-sectional sample of patients with glaucoma (n = 56) and control subjects (n = 54) was obtained. Additional patients (n = 12) were included to examine the relationships between glaucoma, its therapy, and Q of L.

INTERVENTION

The Medical Outcomes Study short form (MOS-20), the Activities of Daily Vision Scale (ADVS), and questions related to glaucoma and side effects of treatment were administered. Descriptive statistics characterized demographic variables and MOS and ADVS scales. Group differences were evaluated using chi-square, Fisher's and Ordinal Exact, Wilcoxon rank-sum, and two-sample t tests. Spearman rank correlations were obtained between MOS-ADVS scores and clinical and demographic variables. Regression was used for multivariate analysis.

MAIN OUTCOME MEASURES

The MOS scores, ADVS scores, visual acuity, visual fields, and demographic variables were measured.

RESULTS

Patients scored significantly lower than did the control subjects in all MOS-20 categories except pain. Differences were physical (-20%), role (-43%), mental health (-10%), general health (-22%), and social (-9%). The only category that was not statistically significant was that of pain (P = 0.075). In the glaucoma subgroup, there were differences between whites and nonwhites in MOS subscales physical, role, social, pain, and health, and ADVS near vision. In patients, current medications and previous surgeries correlated with ADVS subscales night vision, near vision, and glare; visual acuity and fields correlated with MOS subscales physical, role and health, and all ADVS subscales. A multiple regression model including visual acuity and fields, urban residence, and female gender explained 61% of the variability in ADVS overall score.

CONCLUSIONS

The Q-of-L perception differed between patients with glaucoma and control subjects. Increasing field loss, decreased visual acuity, and complexity of therapy correlated with patients' reduction in activities of daily vision.

Treatment of bleb leaks with transforming growth factor-beta in the rabbit model

PURPOSE

The mechanism through which peribleb injection of autologous blood results in resolution of bleb leak in the rabbit model remains unclear. This study evaluates the clinical and histologic effects of peribleb injection of transforming growth factor-beta (TGF-beta) after leak induction in mitomycin-C-treated blebs.

METHOD

Posterior lip sclerectomies treated with mitomycin-C were created in New Zealand White rabbits. On postoperative day 7, a standardized stab incision was performed on all blebs, and the eyes were randomized to receive a peribleb injection of either TGF-beta or of a balanced salt solution.

RESULTS

Injection of TGF-beta was associated with the resolution of bleb leak and maintenance of a functioning bleb in 50% (4 of 8) of treated eyes. The remaining TGF-beta-treated eyes and control eyes demonstrated continued bleb leaks or bleb failures with intraocular pressure returning to preoperative levels. Histologic examination revealed increased peribleb cellularity and denser collagen deposition in the TGF-beta-treated eyes compared with that observed in control eyes.

CONCLUSIONS

Peribleb TGF-beta injections may contribute to healing bleb leaks, but the injections do not appear in this model to be as useful as whole-blood injections.

Results of intraoperative 5-fluorouracil or lower dose mitomycin-C administration on initial trabeculectomy surgery

PURPOSE

This study was conducted to review outcomes in eyes following primary trabeculectomy supplemented intraoperatively with 5-fluorouracil (5-FU) or lower dose mitomycin-C (MMC).

PATIENTS AND METHODS

We retrospectively reviewed the medical records of 73 eyes of 63 patients with progressive, far advanced open angle glaucoma who had undergone initial trabeculectomy with intraoperative application of 5-FU, 50 mg/mL for 5 min (N = 37), or MMC, 200 micrograms/mL for 3-5 min (N = 36), and with at least 12 months follow-up.

RESULTS

Mean preoperative intraocular pressures (IOPs) in the MMC and 5-FU groups were 24.3 +/- 7.6 and 24.6 +/- 9.3 mm Hg, respectively. Postoperatively, IOPs were similar at 6-month interval follow-up examinations in the MMC and 5-FU groups. At an average follow-up of 20.9 months, mean final visit postoperative IOPs were 10.2 +/- 3.6 (p < 0.001) and 9.7 +/- 3.4 mm Hg (p < 0.001) in the MMC and 5-FU groups, respectively, requiring an average of 0.25 and 0.22 antiglaucoma medications per eye, respectively. Interval follow-up complications were similar between groups and included four bleb leaks in the MMC group, and three bleb leaks in the 5-FU group. Visual acuity remained stable in 71 of 73 eyes.

CONCLUSIONS

Both antifibrosis agents provide good intermediate term IOP control and may be appropriate for use in those eyes requiring final "target" IOPs in the low teens or single digits.

Neovascular glaucoma after carotid endarterectomy

The authors examined a patient who had neovascular glaucoma (NVG) shortly after ipsilateral carotid endarterectomy and followed the patient's clinical course. The authors speculate that the sudden reperfusion after endarterectomy that occurs in patients with combined central retinal artery occlusion and carotid occlusive disease may enhance the circulation of preformed angiogenesis factors, leading to the development of neovascularization. The authors recommend frequent and careful surveillance of patients with central retinal artery occlusion associated with carotid occlusive disease if ipsilateral carotid endarterectomy is performed.

Injection of autologous blood for bleb leaks in New Zealand white rabbits

PURPOSE

Bleb leaks after trabeculectomy with antimetabolites can be recalcitrant to therapy. Peribleb autologous blood injections are a moderately successful new treatment modality for such leaks. However, it is unclear what mechanism the injections work to achieve leak resolution.

METHODS

A randomized, prospective study in the rabbit model was undertaken to evaluate further the clinical and histologic effects of peribleb autologous blood injection after leak induction in mitomycin-C exposed blebs, compared to controls that received only peribleb balanced salt solution injections.

RESULTS

In the blood-treated eyes, all bleb leaks healed. Control eyes either demonstrated persistent bleb leaks with shallow anterior chambers or failed blebs that were Seidel negative. Histologic results were remarkable for increased peribleb cellularity and collagen deposition in the blood-treated eyes, compared to controls.

CONCLUSIONS

Peribleb autologous blood injections are associated with bleb leak resolution, increased peribleb cellularity, and collagen deposition in the rabbit model.

Use of scheimpflug photography to study iris configuration in patients with pigment dispersion syndrome and pigmentary glaucoma

PURPOSE

To evaluate the use of Scheimpflug photography in the examination of iris configuration and anterior chamber depth in eyes with pigment dispersion syndrome (PDS) and pigmentary glaucoma (PG).

METHODS

The Nidek EAS 1000 Scheimpflug camera was used to photograph the anterior segment of 12 eyes with PDS/PG, as well as 12 age-matched controls and four eyes with primary open-angle glaucoma (POAG). Anterior chamber depth, iris insertion angle, and iris configuration were evaluated. Five eyes of three patients were serially photographed over 10 min while blinking was prevented.

RESULTS

Patients with PDS/PG showed deeper anterior chambers than age-matched controls or patients with POAG. Nine of 12 PDS/PG eyes showed a concave iris configuration. There were no concave irides noted in control or POAG eyes. Preventing blinking resulted in significant anterior excursion of concave irides in three of the five eyes studied.

CONCLUSIONS

Scheimpflug photography is a useful modality to study iris configuration. These photographs document the presence of a concave iris configuration in some patients with PDS/PG, and support the hypothesis that blinking may be significant in producing this configuration.

Comparison of the Baerveldt glaucoma implant with the double-plate Molteno drainage implant

OBJECTIVE

To compare the 350-mm2 Baerveldt implant with the double-plate Molteno implant in the treatment of eyes with complicated glaucoma.

DESIGN

Retrospective chart review of a consecutive series of drainage implants.

SETTING

University-based referral practice.

PATIENTS

Thirty-four consecutive patients (37 eyes) undergoing glaucoma drainage device implantation because of uncontrolled, complicated glaucoma.

INTERVENTION

Eighteen eyes underwent 350-mm2 Baerveldt implantation and 19 eyes underwent double-plate Molteno implantation.

MAIN OUTCOME MEASURES

Intraocular pressure (IOP) control, visual acuity outcome, and complication rate.

RESULTS

Mean preoperative IOP was 30.2 mm Hg in the Baerveldt group, with an average of 2.7 antiglaucoma medications, and 28.4 mm Hg in the Molteno group, with an average of 2.4 antiglaucoma medications. With an average follow-up of 11.3 months (range, 5 to 16 months), mean IOP at the final visit was 13.1 mm Hg (range, 7 to 21 mm Hg) in the Baerveldt group, with an average of 1.3 medications, and 13.4 mm Hg (range, 8 to 25 mm Hg) in the Molteno group, with an average of 0.8 medications. Final IOP was between 7 and 19 mm Hg in 16 of 18 Baerveldt eyes and in 17 of 19 Molteno eyes. Visual acuity (when it could be checked) remained stable (+/- 2 Snellen lines) in 17 of 17 eyes in the Baerveldt group and in 17 of 19 eyes in the Molteno group. Complications in the Baerveldt group included two cases (11%) of flat anterior chamber after stent removal, one case (6%) of intermittently symptomatic diplopia, and one case (6%) of endophthalmitis. In the Molteno group there were two graft failures (11%) and one eye (5%) with loss of central field.

CONCLUSIONS

Both types of drainage implants provide excellent postoperative IOP control. Early stent removal should be avoided if possible in eyes with Baerveldt implants.

Activation and suppression of fibroblast function

The fibroblast is the central player in the wound repair and scarring processes that occur in the anterior segment of the eye. Glaucoma filtration surgery is the ultimate example of the importance of the wound healing process, as this process is the major determinant of the success of this procedure. We highlight the role of the fibroblast, and discuss some of the growth factors stimulating fibroblast proliferation, migration and extracellular matrix production in the wound environment. We also review current methods of suppressing fibroblast proliferation, the new concepts that have arisen from laboratory studies, and future directions of investigation and treatment.

Intraoperative 5-fluorouracil for filtration surgery in the rabbit

PURPOSE

Postoperative subconjunctival injections of 5-fluorouracil (5-FU) improve the success rate of filtration surgery, but there is still a 20% or greater failure rate at 1 year in pseudophakic and repeat trabeculectomy cases. The injections are inconvenient to give and may produce corneal epithelial toxicity and other side effects. An alternative method for administration of 5-FU is investigated.

METHODS

A masked, randomized, prospective study was undertaken to compare bleb survival and complications in a rabbit model, after either a single intraoperative exposure to 5-FU (50 mg/ml concentration for 5 minutes) or five postoperative injections of 5-FU (5 mg injection on postoperative days 1, 3, 5, 7, and 9), or a combination of both, with controls that received only a 5-minute exposure to distilled water, intraoperatively.

RESULTS

For the control eyes, all blebs were "flat" to masked grading, and intraocular pressure returned to preoperative levels by postoperative day 11. In the group receiving postoperative injections of 5-FU only, blebs were flat and the pressure normalized by postoperative day 14. Rabbits receiving intraoperative 5-FU only, or combined intraoperative and postoperative 5-FU, had consistently higher blebs than the former two groups, and some blebs survived until postoperative day 25. The mean intraocular pressure remained depressed in these groups until postoperative day 21 (P < 0.05 for days 5 through 18). A combination of intraoperative and postoperative 5-FU produced significantly higher blebs than intraoperative 5-FU alone on days 7 to 14.

CONCLUSIONS

Intraoperative application of high-dose 5-FU to the filtration site either as a single 5-minute treatment, or in conjunction with postoperative injections of 5-FU greatly prolongs bleb function after filtration surgery in the rabbit.

Primary open angle glaucomas in the rhesus monkey

Rhesus monkeys from the closed Cayo Santiago colony of the University of Puerto Rico demonstrate elevated (> or = 22 mm Hg) intraocular pressure in a pattern which significantly favours certain maternal lineage groupings. The colony had remained genetically pure since 1938. Of nine matriarchal lineages (matrilines) examined, two had an incidence of ocular hypertension of more than 40% and six of more than 10%. Information on 18 matrilines is currently located in the colony data base which identifies each individual and its vital statistics. In 1990, six animals were moved to the laboratory in Florida. Among those from a low incidence matriline, we found abnormal optic nerve cups, pallor, reduced function of (mainly peripheral) fields, progression and loss of optic nerve axons in the presence of ocular hypertension. In another individual where the cup/disc ratio for the right eye was 0.7 and left eye 0.4 and outflow facility was normal, we excluded all other causes of optic nerve atrophy, and low tension glaucoma was diagnosed. This female was from a matriline with a low incidence of ocular hypertension. Relatively rapid aging (3-4 years/human year) monkeys with ocular hypertension and familial clustering produce a near ideal glaucoma research model.

Effects of intraoperative 5-fluorouracil or mitomycin C on glaucoma filtration surgery in the rabbit

PURPOSE

To establish the effects of single intraoperative exposures to either 5-fluorouracil (5-FU) or two different concentrations of mitomycin C (MMC) on filtration surgery in the rabbit.

METHODS

A prospective, randomized, masked-observer, placebo-controlled study was performed to compare the effects on filtration surgery in rabbits of a single 5-minute intraoperative exposure to 5-FU (50 mg/ml), MMC (0.2 mg/ml), or MMC (0.4 mg/ml) with control eyes treated with distilled water.

RESULTS

Intraocular pressures (IOPs) remained lower for longer and bleb survival was increased (P < 0.05) with all three treatments compared with control eyes. The effect of 5-FU was more transient than MMC. Bleb survival was prolonged in the following order: MMC 0.4 > MMC 0.2 > 5-FU 50 mg/ml. At 30 days, blebs were present in 100% of eyes treated with MMC 0.4 mg/ml, 60% of eyes treated with MMC 0.2 mg/ml, and 0% of eyes treated with 5-FU 50 mg/ml or distilled water. The blebs in the eyes treated with MMC were thinner, and significant complications (endophthalmitis, transient corneal opacification and neovascularization, and a presumed bleb leak) only occurred in the eyes treated with MMC 0.4 mg/ml.

CONCLUSIONS

The authors' results suggest that 5-FU and MMC at these concentrations, delivered as a single intraoperative dose, prolong the survival of filtration surgery for different lengths of time in the rabbit, which is a model that normally exhibits aggressive healing and rapid failure of filtration surgery. The implications of these potentially titratable effects for filtration surgery in different categories of patients are discussed.