Blepharokeratoconjunctivitis in children: diagnosis and treatment

AIM

Blepharokeratoconjunctivitis (BKC) is a poorly described entity in children. This study characterises this syndrome in childhood and evaluates epidemiology, clinical grading, and treatment strategies.

METHODS

44 children (20 white, 22 Asian, 2 Middle Eastern, median age 5.4 (range 1-14) years) with a diagnosis of BKC were followed for a median of 7 years. Diagnostic criteria included recurrent episodes of chronic red eye, watering, photophobia, blepharitis including recurrent styes or meibomian cysts, and a keratitis. Clinical features were graded as mild, moderate, or severe. The lids and conjunctiva were cultured. The treatment regimen incorporated lid hygiene, topical and/or systemic antibiotics, and topical corticosteroids.

RESULTS

The disease was most severe in the Asian and Middle Eastern children (p <0.001), who had a statistically higher risk of subepithelial punctate keratitis (p = 0.008), corneal vascularisation (p <0.001), and marginal corneal ulcerations (p = 0.003), than the white group. 15 children had culture positive lid swabs. Most children had a reduction in symptoms and signs with treatment, and progression of disease after the age of 8 was rare.

CONCLUSIONS

BKC in children can be defined as "a syndrome usually associated with anterior or posterior lid margin blepharitis, accompanied by episodes of conjunctivitis, and a keratopathy including punctate erosions, punctate keratitis, phlyctenules, marginal keratitis, and ulceration." BKC is common in children in a tertiary referral corneal and external diseases clinic, with the more severe manifestations in the Asian and Middle Eastern populations. Therapy is effective and loss of sight can be prevented in most cases.

The Endophthalmitis Population Study of Western Australia (EPSWA): first report

BACKGROUND/AIM

Over the period of 19 years to 1999, cataract surgery numbers increased 6% per annum in Western Australia (WA), promoted by the convenience, efficacy, and general safety of outpatient phacoemulsification surgery. Although endophthalmitis is an uncommon complication, it is a major cause of post-cataract surgery blindness. The present population study investigates not only the prevalence of endophthalmitis but provides an accurate incidence of endophthalmitis in WA over the same period.

METHODS

Using the hospital morbidity data system (HMDS) of the WA Record Linkage Project, and cross validating against three independent databases (anaesthetic and microbiological databases and surgeons' logbooks) the authors examined 698 case notes that were potentially cases of endophthalmitis for the period 1980 to June 1999. As the database linkage was incomplete for 1999, only the 188 confirmed cases to 1998 were included in the present study. Additional case note validation was performed to confirm the correct codes for the cataract surgical procedure.

RESULTS

Despite changes in surgical technique and prophylaxis over the study period of 19 years, the incidence of endophthalmitis remained largely unchanged, averaging one in 500 surgical cases overall. However, the incidence fluctuated over time and varied with the location of surgery ranging from 0.65 per 1000 operations to 16.4 per 1000 operations.

CONCLUSION

These data highlight previously undescribed temporal and geographic variations in the incidence of endophthalmitis. It is uncertain whether the wide variation in prophylactic practices throughout the ophthalmic community has any bearing on the incidence of endophthalmitis.

A simple corneal perfusion chamber for drug penetration and toxicity studies

AIMS

Corneal perfusion chambers are important tools in the development and assessment of ophthalmic drugs. The aim of this study was to design and test a modified perfusion chamber suitable for topical application of drugs to isolated corneoscleral preparations, and which allowed continuous monitoring of endothelial cell function.

METHODS

A polycarbonate and stainless steel perfusion chamber was designed to clamp corneas in a horizontal plane suitable for topical drug delivery. Endothelial cell function was assessed by ultrasonic pachymetry and specular microscopy during perfusion. Epithelial barrier function was assessed by penetration of fluorescein. Leakage was examined by measuring penetration of a large protein, IgG. Tissue architecture after perfusion was examined by conventional histology.

RESULTS

Corneas maintained a functionally and morphologically intact endothelial monolayer during perfusion periods of up to 14 hours. The epithelial barrier function was well preserved. The tissue clamp sealed the preparation effectively against leakage of macromolecules.

CONCLUSION

The new chamber device forms a reliable tool for in vitro drug penetration and toxicity studies in isolated perfused corneoscleral tissue.

Pharmacokinetics of ciprofloxacin in the human eye: a clinical study and population pharmacokinetic analysis

Ciprofloxacin, a fluoroquinolone antibiotic active against a wide variety of bacteria, is one of a few antibiotics which enters the human eye after oral administration. However, little is known about its pharmacokinetics in the human eye. One or two oral doses of 750 mg of ciprofloxacin (at a 12-h interval) were administered to 48 patients at various times prior to ocular surgery. Clotted blood, aqueous, and vitreous were collected at surgery, and the concentrations of ciprofloxacin were assayed by high-performance liquid chromatography. Our data were combined with those of others, and a population pharmacokinetic analysis was conducted. The concentrations of ciprofloxacin in both aqueous and vitreous were lower than those in serum and peaked at a later time. The pharmacokinetics of ciprofloxacin in aqueous and vitreous were fitted to a compartmental model in which the antibiotic was transferred into and out of the two compartments (aqueous and vitreous) by first-order processes. Population pharmacokinetic software, P-Pharm, was used to calculate the mean half-lives of the loss of ciprofloxacin from aqueous and vitreous, which were 3.5 and 5.3 h, respectively. At steady state, the mean ratios of then concentrations in aqueous and vitreous to the concentrations in serum were 23 and 17%, respectively. After the administration of one or two doses of 750 mg of ciprofloxacin, the concentrations in both aqueous and vitreous in a number of patients were lower than the MICs at which 90% of isolates are inhibited (0.5 mg/liter) for common intraocular bacterial pathogens. Simulations of concentrations in the eye after the administration of higher doses (1,500 mg of ciprofloxacin as a single dose, two doses of 750 mg 2 h apart, and 750 mg every 6 h) indicated that in approximately 20% of patients the concentrations would still be below 0.5 mg/liter. Although oral ciprofloxacin may be a beneficial adjunctive therapy, the use of oral ciprofloxacin alone may not be adequate for perioperative prophylaxis or for treatment of bacterial endophthalmitis.

Biofilm on scleral explants with and without clinical infection

PURPOSE

Biofilm is a glycocalyx matrix secreted by microorganisms that confers protection against host defenses and antimicrobial treatment. Biofilms have been implicated in the persistence of scleral buckle infections. This study aimed to evaluate the incidence of biofilm growth on scleral explants and the relationship to explant infection.

METHODS

Scleral explants were obtained following removal for infection or extrusion or during repeat surgery. Explants were fixed with rhuthenium red and examined by scanning electron microscopy to visualize the glycocalyx.

RESULTS

A total of 28 explants were analyzed. Ten were removed because of either infection or extrusion and 18 were removed during repeat surgery. The mean time to removal of explants was 36 months in the infection/extrusion group and 12 months in the others. Biofilm was identified on five explants-two removed because of infection/extrusion and three for surgical indications. Bacterial elements were identified in all biofilms.

CONCLUSIONS

Biofilm was identified on explants removed because of infection or exposure and on explants removed for technical reasons at repeat surgery. This implies that bacterial contamination and biofilm formation occur without exposure of the explant, probably due to inoculation at the time of initial surgery. Biofilms may contribute to the persistence of scleral explant infections but a causative role in buckle extrusion is unproved.

Etoposide as a virocidal anticytomegalovirus therapy: intravitreal toxicology and pharmacology in rabbits

BACKGROUND

Although Cytomegalovirus (CMV) retinitis is now a common intraocular infection, current therapy is only virostatic so ongoing treatment is required. Etoposide was found to be virocidal for CMV in laboratory experiments and it might prove to be beneficial clinically. We investigated the toxicity and intraocular concentration of etoposide (VP16) and its new analogue etoposide-phosphate (VP16P) following intravitreal injections in rabbit eyes.

METHODS

First a sequential dose-response was assessed with flash electroretinogram for both eyes of light- and dark-adapted rabbits (n = 7; one rabbit for each dose) over a range of light intensities before and after intravitreal injection of VP16 or VP16P to one eye; the other eye was injected with normal saline as a control. A multidose study was then performed on four rabbits. A non-toxic dose of VP16P (50 or 75 g) was injected into the vitreous of one eye on four occasions 1 week apart. A photopic electroretinogram was performed before the first injection and 6 weeks after the last injection. All the eyes from the electroretinogram studies were fixed in formalin, placed in paraffin, then stained with haematoxylin and eosin and examined under a light microscope. To determine the time-course of the intraocular concentrations of VP16P a sequential pharmacokinetic study was performed using a further 12 rabbits. Each rabbit was injected with 50 g VP16P to one eye and 75 g VP16P to the other eye. Three of these rabbits were killed at 1, 3, 6 and 9 h after injection. Samples of vitreous were assayed for both VP16 and VP16P using HPLC. An in vitro dose response assay was performed using third-passage bovine retinal pigment epithelial (RPE) cells cultured in Dulbecco's modified Eagles medium with fetal calf serum. The effect of a log-dose increment of VP16P on the RPE cell proliferation was assessed using tritiated thymidine incorporation.

RESULTS

The electroretinogram studies suggested that VP16 was toxic even with the 10 g dose. For VP16P a toxic effect was noted following injection of a single dose greater than 100 g. Multiple injections of 50 or 75 g VP16P did not produce a toxic response. Histological examination demonstrated significant abnormality only with the 500 g dose of VP16 or VP16P. VP16P was rapidly metabolized to VP16 in the eye, producing concentrations of 2.0 g/mL or more for up to 9 h following a 75-microg dose. This suggests that the electroretinogram findings following VP16 injections were confounded by a toxic effect of the ethanol solvent (which is absent from the VP16P preparation). VP16P was quite potent, the ID50 was about 0.1 g/mL for bovine RPE cells in the in vitro assay.

DISCUSSION

These results indicate that multiple 75-gVP16P intravitreal injections were not toxic to the rabbit eye and provide a therapeutic intraocular concentration for up to 9 h after the injection.

Risk factors for treatment outcome of suspected microbial keratitis. Ofloxacin Study Group

BACKGROUND

Primary treatment for suspected microbial keratitis is generally successful. Although risks such as contact lens use are well recognised as causative factors for microbial keratitis, little is known about the risk factors that influence treatment outcome. The present study evaluates the risk factors assessed at diagnosis as prognostic indicators of primary treatment failure.

METHODS

Patients were prospectively enrolled in the ofloxacin treatment trial and data concerning symptoms, treatments, past and concurrent eye disease were collected along with the measurement of corneal ulcer size at the slit lamp. All patients were scraped for microbiological investigation, and treated with either ofloxacin (0. 3%) or standard therapy of fortified cefuroxime and gentamicin drops. Treatment success was complete healing of the ulcer with zero dimensions of the epithelial defect within 2 weeks of start of treatment. The important prognostic indicators were selected by comparison among those who failed treatment, had delayed healing, or were culture positive with other patients using univariate and stratified analysis. These were then used in a Poisson model for multiple regression analysis to estimate the relative risk of the main prognostic variables.

RESULTS

Of the 118 patients enrolled in the study, 14 were identified as primary treatment failures, 17 had slow healing, and 15 indolent ulcers. There were 49 culture positive patients. The multivariate analysis identified that large culture positive ulcers in patients 60 years or older had 5.5 times the risk of primary treatment failure (p<0.001). Significant predictors of slow healing were previous ocular disease and a positive culture; significant predictors of indolent ulceration were previous ocular disease and steroid use at diagnosis; the main predictor of a culture positive result was ulcer size.

CONCLUSIONS

Elderly patients with large ulcers were more likely to be culture positive, fail primary therapy, and require surgical intervention. A positive microbial culture provided prognostic information regardless of the organism isolated. However, this information was of less value for those with small ulcers and for younger patients.

The systemic absorption of adrenaline from posterior segment infusion during vitreoretinal surgery

BACKGROUND/PURPOSE

Adrenaline infused into the posterior segment of the eye during vitreoretinal surgery may be absorbed and give rise to unwanted cardiovascular effects. We sought to establish whether significant amounts of adrenaline are systematically absorbed.

METHODS

This study was prospective and double-masked, with patients randomised into two groups. The first group received a posterior segment infusion containing Hartmann's solution alone (Hs group) and the second group received a posterior segment infusion of Hartmann's solution containing 0.5 ml of 1:1000 (0.5 mg) adrenaline per 500 ml (Hs + Ad group). Pre-medication and anaesthetic techniques were standardised for all patients. Venous blood samples were collected prior to induction, 5 min following intubation and 5, 10, 15 and 30 min following the commencement of the infusion. Samples were analysed for adrenaline levels using high-performance liquid chromatography.

RESULTS

Ten patients were studied: 4 in the Hs group and 6 in the Hs + Ad group. The mean dose of adrenaline administered in the Hs + Ad group was 655.08 nmol (0.12 mg). The median serum adrenaline level following infusion for the Hs + Ad group was 0.15 nmol/l (LQ = 0.100, UQ = 0.360) and the median serum adrenaline level for the Hs group was 0.10 nmol/l (LQ = 0.100, UQ = 0.350). There was no overall statistical difference in the levels of serum adrenaline between the two groups, and furthermore adrenaline levels remained within physiological parameters for both groups.

CONCLUSION

There does not appear to be significant adrenaline absorption from posterior segment infusion. Continued caution should be exercised, however, as idiosyncratic reactions may still occur.

High-dose (2000-microgram) intravitreous ganciclovir in the treatment of cytomegalovirus retinitis

OBJECTIVE

The authors prospectively studied visual outcome, relapse, complications, and survival of patients with acquired immune deficiency syndrome (AIDS)-related cytomegalovirus (CMV) treated with high-dose intravitreous ganciclovir (2 mg/0.1 ml) injections. The outcomes were compared with those of patients treated with standard doses of intravenous ganciclovir in the same institution. The histopathologic and electrophysiologic effects of high-dose intravitreous ganciclovir injections in rabbits also were studied.

DESIGN

A nonrandomized case series.

PARTICIPANTS

A total of 42 patients (74 eyes) were treated with intravitreous injections and 18 patients (27 eyes) were treated with intravenous ganciclovir. Five eyes of three New Zealand white rabbits were injected with ganciclovir, and the sixth eye was a control specimen.

INTERVENTION

Patients treated with intravitreous injections received twice-weekly doses of 2 mg/0.1 ml ganciclovir for 3 weeks, then weekly injections. Patients treated with intravenous ganciclovir received standard doses. Patients were monitored with regular examinations. Rabbit eyes were given intravitreous injections of 1 mg/0.1 ml of ganciclovir weekly for 4 weeks.

MAIN OUTCOME MEASURES

Assessments of vision, retinal inflammation, and survival were made. Electroretinograms were performed on the rabbit eyes, and they were processed for light and electron microscopy.

RESULTS

In the intravitreous group, visual acuity (VA) was stable in 64 of 74 eyes, 5 improved, and 5 deteriorated. Sixty-three (85%) of 74 eyes had final VA of 20/20 to 20/40. Relapse occurred in five eyes (7%; median time, 42 weeks). There were three cases of endophthalmitis. Median survival after diagnosis of CMV retinitis was 36 weeks. In the intravenous group, VA was stable in 18 eyes, 0 improved, and 9 deteriorated. Sixteen (59%) of 27 eyes had final VA of 20/20 to 20/40. Relapse occurred in 15 eyes (56%) at a median time of 21 weeks. Median survival was 21 weeks. The rabbit studies showed no evidence of toxicity.

CONCLUSION

High-dose intravitreous ganciclovir effectively suppressed CMV retinitis, preserved vision, and prevented relapse without deterioration in survival.

Polymerase chain reaction analysis of corneal epithelial and tear samples in the diagnosis of Acanthamoeba keratitis

PURPOSE

Acanthamoeba is an uncommon cause of corneal infection in which the best visual outcome follows prompt diagnosis and a long course of appropriate antimicrobial therapy. Because conventional detection techniques for Acanthamoeba have certain limitations, we investigated the ability of the polymerase chain reaction (PCR) to confirm the clinical diagnosis of Acanthamoeba keratitis, with the ultimate aim of achieving early diagnosis.

METHODS

Using two different pairs of primers, PCR was performed on representative cultured Acanthamoeba isolates to confirm the assay's ability to amplify Acanthamoeba DNA from a wide range of acanthamoebae. Subsequently, corneal epithelial samples from 19 patients and tear samples from 12 patients with Acanthamoeba keratitis were analyzed by PCR for the presence of Acanthamoeba DNA.

RESULTS

Acanthamoeba DNA was amplified by PCR from 16 (84%) of 19 corneal epithelial samples, whereas Acanthamoeba was cultured from 10 samples (53%), all of which were PCR positive. Tear samples from 8 (66%) of 12 patients were positive on PCR testing, and one tear sample was PCR positive, whereas the corresponding epithelial biopsy had yielded a negative PCR result. Samples from culture-positive patients were positive on PCR testing more frequently than those from culture-negative patients (10/10 culture-positive corneal epithelial and 5/7 [71%] culture-positive initial tear samples versus 6/9 [66%] culture-negative corneal epithelial and 2/5 [40%] culture-negative tear samples). All control epithelial (n = 15) and tear (n = 15) samples yielded negative results.

CONCLUSIONS

PCR was a more sensitive diagnostic test than a culture for Acanthamoeba keratitis, and the use of two different primers achieved better sensitivity than a single set. A PCR of a tear sample also may be a useful complementary test and, in combination with PCR of epithelial samples, would prove particularly helpful in confirming the clinical diagnosis in culture-negative cases.

Patterns of peri-operative prophylaxis for cataract surgery: a survey of Australian ophthalmologists

BACKGROUND

Although peri-operative prophylaxis to prevent endophthalmitis is commonly practised by ophthalmologists, no one method has clearly been demonstrated to be more effective than another. We surveyed 570 Fellows of the Royal Australian College of Ophthalmologists to determine what their methods of prophylaxis were and whether these differed for patients who developed endophthalmitis.

METHODS

The questionnaire asked about the types of antibiotics and other methods of prophylaxis used before, during and after cataract surgery. Of those who reported cases of endophthalmitis, we asked specifically about the methods of prophylaxis used for those patients.

RESULTS

The response was 89% and the incidence of endophthalmitis was calculated as 0.11%. There was little difference in the methods of prophylaxis used by those who reported endophthalmitis compared with others, but pre-operative antibiotics were used more commonly by those who reported the disease (P = 0.06). Surgeons who had practised for 20 years or more reported a lower rate of endophthalmitis than others, as did those who performed more than 300 cataract operations per year. However the pattern of prophylaxis used by these two sub-groups was quite divergent. Differences in the methods of prophylaxis had no bearing on the development of endophthalmitis, with the exception that subconjunctival antibiotics were used less often in those patients who developed the disease (P = 0.03).

CONCLUSIONS

The results of the present study provide no clear answer regarding appropriate peri-operative prophylaxis. The wide range of prophylactic regimens used suggests that no one method is superior to another. Formal case-controlled studies are required to identify which method would be most efficacious.

Reliable keratometry with a new hand held surgical keratometer: calibration of the keratoscopic astigmatic ruler

AIM

Some surgeons consider hand held surgical keratometers unreliable. This may be due to incorrect use through not realising that the distance that the keratometer is held from the cornea influences the shape of the image. When a keratometer is held closer to the astigmatic cornea, the elliptical image will appear more circular, particularly for larger degrees of astigmatism. However, the keratoscopic astigmatic ruler (KAR) has design features that correct the hitherto unrecognised problems with the use of a hand held keratometer. This study assesses the reliability and accuracy of measurement of astigmatism using the KAR.

METHODS

The KAR and the Bausch & Lomb keratometer (B&L) were compared using six back surface toric cut contact lens blanks representing 1 to 6 dioptres of astigmatism. Two observers (one experienced in the use of the keratometers, the other a novice) took eight randomly repeated "masked" measurements of each lens blank with the KAR and four measurements with the B&L in a similar fashion.

RESULTS

There was no difference between the measurements with either instrument by each of the observers (p = 0.95, ANOVA). The standard error of measurement for the KAR was 0.59 D, for the B&L, 0.31 D. The intraclass correlation coefficient of reliability for the KAR was 0.90 and for the B&L it was 0.97. The coefficient of repeatability for the KAR was plus or minus 0.83 D, and for the B&L plus or minus 0.77 D. The interobserver reliability for the KAR was 0.898, and for the B&L, 0.975.

CONCLUSION

These results suggest that the KAR has good reliability and reproducibility and compares favourably with the B&L keratometer. Inexperience with use does not affect reliability.

Natural history of recurrent erosion syndrome--a 4 year review of 117 patients

AIMS/BACKGROUND

Recurrent erosion syndrome encompasses a group of mixed aetiologies for which there are a number of methods of management which may influence the course of the disease.

METHODS

The outcomes of a cohort of patients initially treated with topical lubricants were studied. 117 consecutive patients presenting over 1 year with a history of recurrent erosions were enrolled, baseline characteristics were documented, and treatment with lubricants was initiated. Patients were surveyed 4 years later inquiring about symptoms and treatments required.

RESULTS

A total of 94 (80%) of the initial cohort were contacted. The mean age was 44 years and the sex distribution was 44 males to 50 females. The mean period of follow up was 48 months. 55 (59%) were still symptomatic with attacks occurring at a median frequency of 60 days. 13 patients (24%) complained of an episode at least every week and 28 patients (51%) suffered at least every month. The median pain score (analogue scale of 1-10) was 2.5. Seventy five per cent (n = 21) of patients with epithelial basement membrane dystrophy (EBMD) were symptomatic compared with those with a traumatic aetiology among whom 46% (n = 28) were symptomatic. This difference was significant (p = 0.02). Those with EBMD were more likely to be continuing to use topical lubricants than the trauma group.

CONCLUSION

Patients with a traumatic aetiology are less likely to suffer chronic recurrent erosion syndrome than those with EBMD.

Outcome of acanthamoeba keratitis treated with polyhexamethyl biguanide and propamidine

OBJECTIVE

This study investigates the clinical outcome of Acanthamoeba keratitis treated with polyhexamethyl biguanide (PHMB) and propamidine isethionate (Brolene).

DESIGN

A retrospective review of all patients treated for Acanthamoeba keratitis between September 1992 and February 1995 was carried out. All patients were treated with PHMB 0.02% and propamidine 0.1% hourly for 3 days, the frequency reduced to four to six times daily according to clinical response.

MAIN OUTCOME MEASURES

Age, gender, result of laboratory investigation, duration of disease before diagnosis, visual acuity (VA) pretreatment and post-treatment, need for keratoplasty, and presence of adverse reaction were measured.

RESULTS

One hundred eleven cases were identified in 105 patients (60 male, 45 female; mean age, 32). Ninety-two percent of infections were in contact lens wearers. The clinical diagnosis was confirmed by corneal culture or histopathology in 64 cases (57.7%). The diagnosis was made "early" (within 28 days) in 65 cases (58.6%). Twenty-one (18.9%) were "intermediate" (28 days-2 months) and 20 (18%) were "late" (> 2 months) diagnoses. Overall post-treatment VA was 6/12 or better in the majority (88/111, 79.3%) of cases, and 18 (16.2%) had VA of 6/36 or worse. The VA of > or = 6/12 was achieved by 90.8% of the early, 71.4% of the intermediate, and 65% of the late groups. Clinical relapses occurred in 19 patients on reducing the therapy. Treatment toxicity was never serious and consisted only of stinging or superficial punctate keratopathy. Keratoplasty was indicated in only ten patients, and disease activity was controlled adequately in all patients before grafting.

CONCLUSIONS

Combined treatment with PHMB and propamidine is well tolerated, nontoxic, and effective. Typically, visual outcome is favorable and the requirement for keratoplasty reduced markedly.

A method of drop administration

Self-administering drops can be a daunting task for many patients. The authors describe a method of drop administration that allows a patient to accurately place drops without the need for special devices or touching the eye. With the bottle of drops held upside down, the back of the thumb is rested on the forehead to stabilize the bottle. The bottle tip can be seen over the eye. The other hand retracts the inferior lid to catch the drop. Poor compliance is common and is often caused by difficulties with drop administration. This simple technique may improve compliance.

Topical interferon alpha 2b for corneal haze after excimer laser photorefractive keratectomy. The Melbourne Excimer Laser Group

PURPOSE

To determine whether topical interferon alpha 2b (IFN-alpha) prevents corneal haze after excimer laser photorefractive keratectomy (PRK).

SETTING

Tertiary referral ophthalmic hospital.

METHOD

A prospective, double-blind, placebo-controlled, randomized study of 31 patients was undertaken. After surgery in a single institution, patients received a drop of either a placebo or IFN-alpha (5 x 10(6) IU/ml) four times daily for 4 weeks. The main outcome measures were corneal haze, refraction, and visual acuity.

RESULTS

The major side effect of interferon alpha treatment was a significant delay in epithelial healing by a mean of 2 days. The means of the average post-treatment clinical scores for haze in all patients up to 12 months after surgery were 0.46 +/- 0.25 for the IFN-alpha group and 0.64 +/- 0.43 for the placebo group (P = .20). Of patients with a correction of greater than 5.00 diopters (D), the IFN-alpha group had significantly less haze over the course of the study (0.39 +/- 0.23 versus 0.98 +/- 0.50; P = .03). After 12 months, the mean absolute spherical equivalent in the two groups was not significantly different (1.02 +/- 1.13 D versus 1.44 +/- 2.64 D). There was a tendency toward better uncorrected visual acuity in the INF-alpha group (P < .10, Kolmogorov-Smirnov).

CONCLUSION

Topical IFN-alpha may merit further investigation as a treatment to reduce corneal haze after excimer laser PRK for corrections greater than 5.00 D.

High dose intravitreal ganciclovir injection provides a prolonged therapeutic intraocular concentration

BACKGROUND

Although intravitreal high dose ganciclovir has previously been found to provide excellent control of cytomegalovirus (CMV) retinitis, little was known about the vitreous concentrations of ganciclovir after a 2 mg intravitreal injection.

METHODS

Eleven vitreous samples were taken from seven patients with CMV retinitis at 24 and 72 hours after a 2 mg intravitreal injection of ganciclovir and the concentration of ganciclovir was measured by high performance liquid chromatography.

RESULTS

The mean concentration of ganciclovir at 24 hours was 143.8 mg/l (95% confidence interval 97.8-190) and at 72 hours was 23.4 mg/l (95% CI 0-49.7). The half life ranged from 11.9 to 26.3 (mean 18.8) hours in the four patients who had two samples taken. The mean half life calculated from the mean concentrations at 24 and 72 hours was 18.3 hours, so the calculated mean concentration at 7 days was 0.6 mg/l.

CONCLUSIONS

This suggests that it takes about 7 days to eliminate the intravitreal ganciclovir, and that it is not likely to accumulate with weekly injections. The intravitreal concentrations achieved with high dose therapy remained above the ID50 for CMV (0.25-1.22 mg/l) for up to 7 days.

Improving drop administration by patients

1. Patients that have difficulties with drop application may have poor compliance with therapy. We studied the effectiveness of teaching a technique of drop administration that allows the patient to steady the hand and observe the dropper tip during application. 2. Comparing the group taught the technique of application with another group who had their drops applied by a home caregiver, we found that those taught the technique were as reliable as the others in the delivery of their drops. 3. Although some patients will be physically incapable of applying drops, we found that the technique we describe in the present study enables effective and safe delivery of drops.

Intraoperative semiquantitative keratometry using the keratoscopic astigmatic ruler

Intraoperative keratometry enables the surgeon to set an appropriate amount of corneal astigmatism with the suture tension. Errors in estimating or measuring the astigmatism can occur with hand-held keratometers because the distance an object is held from an astigmatic cornea influences the shape of the elliptical image. Thus hand-held instruments should be held at a calibrated distance. We have designed a new hand-held keratometer, the keratoscopic astigmatic ruler, to assess the magnitude of corneal astigmatism. It consists of a rack of elliptical keratoscopic lenses corresponding to increasing magnitudes of astigmatism and is made from inexpensive autoclavable injection-molded plastic. The ruler's keratoscopic lenses refract light, creating a real aerial image above the cornea that produces a bright and easily determined corneal reflection. The ruler incorporates a sight to allow the user to hold the ruler at the correct distance.

High dose intravitreal ganciclovir for CMV retinitis: a shelf life and cost comparison study

BACKGROUND

It was previously found that high dose intravitreal ganciclovir provided superior treatment of cytomegalovirus retinitis compared with intravenous treatment. This study examined the stability and solubility of the ganciclovir solution to determine the shelf life of prepared solution, and compared the cost of intravitreal with intravenous therapy.

METHODS

For the solubility studies high performance liquid chromatography was used to determine the ganciclovir concentration in various solutions. Measurements were taken of freshly made 20 mg/ml solution, the same solution stored at room temperature or frozen for 10, 17, and 24 days, after the solution was filtered, and after it was heated at 56 degrees C. For the cost comparison analysis the cost of 22 patients treated exclusively with intravitreal high dose ganciclovir was compared with cost estimates for the same patients treated with a standard intravenous therapy regimen over the same time.

RESULTS

There was little variation in the concentration of ganciclovir regardless of the storage conditions, suggesting that the 20 mg/ml solution was very stable. The heating and filtering experiments suggest that maximum solubility was achieved both in the freshly prepared and thawed frozen stored solution. The total cost of the intravitreal treatment was Aus $172,435 and the estimate of intravenous treatment was Aus $490,521. This represents a total saving of $318,086 (65%), or $14,458 per patient. The average number of weeks of treatment for each patient was 27.9 (613 weeks/22 patients), so the saving per patient per year was $29,946.

CONCLUSION

High dose intravitreal ganciclovir therapy may be administered in a very cost effective way, which along with its acceptability, safety, and clinical efficacy make it an attractive method of treatment of CMV retinitis.

A comparison of two semi-quantitative surgical keratometers: the modified Hyde ruler and the Barrett keratoscope with "astigmatic dial"

The Hyde astigmatic ruler is an inexpensive, semiquantitative, hand-held, surgical keratometer that we modified by geometrically calculating the correct shape of its ellipses. The Barrett keratoscope is a cheap, disposable, qualitative keratometer that, unlike the Hyde ruler, produces a bright corneal image. We designed a transparent overlay, or "astigmatic dial," to use with the keratoscope. This overlay determines the magnitude of astigmatism and sets the distance the keratoscope is held from the cornea by direct comparison with the corneal image. Using a model cornea, we compared our modified Hyde ruler with the Barrett keratoscope and astigmatic dial to determine the accuracy of measurement provided by each. Both instruments had good predictive values for the true astigmatism; however, the Barrett keratoscope/astigmatic dial provided more consistent measurements of the astigmatism. We believe the keratoscope and dial provide a cheap, convenient, and accurate alternative to the more expensive microscope-mounted keratometers.

Clinical utility of the Barrett keratoscope with astigmatic dial

Intraoperative keratometry allows some degree of control over corneal astigmatism during cataract surgery. I describe the clinical use of the Barrett keratoscope combined with an astigmatic dial that quantifies the information obtained by this simple, inexpensive, hand-held surgical keratometer. Based on a comparison of intraoperative measurements with those taken after extracapsular cataract surgery with an automated keratometer, I conclude that intraoperative keratometry reliably predicted the postoperative astigmatism. For those who had the intraocular pressure (IOP) set between 15 and 20 mm Hg intraoperatively, the mean deviation of the first postoperative measurement from the intraoperative measurement of astigmatism was +/- 1.03 D (standard error, 1.56 diopters; 95% confidence interval 0.712 to 1.35 D). When the IOP was not set, the postoperative astigmatism differed from the intraoperative reading by more than 2.00 D for 50% of the cases. Setting the IOP prior to intraoperative keratometry significantly improved the reliability of the measurement. Intraoperative keratometry by the simple device used in this study is of sufficient utility to allow the surgeon to adjust for the predicted changes in the corneal astigmatism at the time of surgery.

Effect of topical interferon-alpha 2b on corneal haze after excimer laser photorefractive keratectomy in rabbits

BACKGROUND

Anterior corneal stromal keratocytes are activated by excimer laser photorefractive keratectomy resulting in haze with healing of the ablated area. In some eyes, this causes a visible haze or scar on the cornea, and an unpredictable regression of the myopic correction following refractive ablations.

METHODS

Following a 6.00-diopter excimer laser photorefractive keratectomy to both eyes, 16 rabbits were treated for 5 weeks with interferon-alpha 2b drops four times a day to one eye only. Eight of these rabbits were treated with dexamethasone drops four times a day to both eyes. Using a standard grading scale for haze, the corneas were examined and the haze graded weekly.

RESULTS

The observed corneal haze was significantly reduced in the treated eyes by the application of topical interferon-alpha 2b drops (p = .004), and topical dexamethasone drops (p < .001). Topical dexamethasone also produced less haze in combination with interferon-alpha 2b than when used alone (p = .035). There was continuing resolution of the corneal haze in those rabbits observed for 7 weeks after the cessation of the drops. Topical interferon-alpha therapy was not toxic to the rabbit eye and was not associated with delayed reepithelialization after the laser procedure.

CONCLUSION

Topical interferon-alpha 2b appears to reduce the corneal haze produced by excimer laser photorefractive keratectomy in rabbits.

Prevention of intraocular pressure rise following intravitreal injection

The intraocular pressure change produced by an intravitreal injection of ganciclovir, 2 mg in 0.1 ml, was studied in patients with cytomegalovirus retinitis. Using a Tono-pen XL to measure the intraocular pressure (IOP) of four patients (six eyes) we found the mean pressure immediately following injection was 44.5 mm Hg. Measurements taken on separate occasions after a 30 mm Hg decompression of the eye for 15 minutes before the injection showed a mean IOP of only 20.6 mm Hg after the injection. Mercury bag decompression of the eye significantly reduced the rise in IOP following intravitreal injection (difference in the mean IOP rise = 26.4 mm Hg, df = 54, t = 7.67, p < 0.001). Without ocular decompression before injection, all patients complained of temporary loss of vision, and reflux of the injection solution was frequently observed. Use of ocular decompression also reduced the discomfort of the injection. Throughout the full course of treatment by this means there were no adverse effects on the visual acuity. This technique is recommended to those performing intravitreal injections.

High dose intravitreal ganciclovir in the treatment of cytomegalovirus retinitis

OBJECTIVE

To assess the role of intravitreal administration of high doses of ganciclovir as a supplement and alternative to intravenous administration in the treatment of cytomegalovirus (CMV) retinitis in patients with acquired immunodeficiency syndrome (AIDS).

DESIGN

A retrospective study of visual outcome, relapse and complications of intravenous and high dose intravitreal administration of ganciclovir alone and in combination.

METHOD

Twenty-three patients with AIDS and CMV retinitis (37 eyes) were examined by the authors and notes, fundal drawings and photographs reviewed. Initially patients were treated with intravenous ganciclovir alone and given supplementary intravitreal therapy for relapse or vision-threatening retinitis; however, later patients were managed with combination maintenance ganciclovir or maintenance intravitreal treatment alone.

RESULTS

Relapse and loss of vision occurred frequently in patients treated with intravenous ganciclovir alone or in combination with intermittent intravitreal therapy. Eyes managed with maintenance high dose intravitreal ganciclovir alone or in combination with intravenous treatment did not relapse or lose vision. The most important complication of intravenous administration of ganciclovir was neutropenia (73% of patients), whereas that of intravitreal therapy was endophthalmitis (three eyes).

CONCLUSION

High dose ganciclovir given intravitreally effectively suppressed CMV retinitis and preserved vision without adverse systemic effects or deterioration of quality of life.

A quantitative scale for the Barrett keratoscope

By allowing the surgeon to measure and modify corneal curvature during wound closure, intraoperative keratometry can reduce postoperative astigmatic errors. A number of keratometric devices have been developed over the last 10 years, each offering a compromise between cost, accuracy and ease of use. The Barrett keratoscope is a simple, inexpensive hand-held device which gives a qualitative indication of the degree of astigmatism. Addition of a transparent overlay, as described in this paper, sets the distance at which the keratoscope is held and allows the magnitude of the astigmatism to be determined, thereby enabling refined adjustment of the suture tension during wound closure. We describe the error in estimation of astigmatism due to the effect of the distance at which the keratoscope is held from the cornea.