Comparison of deep lamellar keratoplasty and penetrating keratoplasty in patients with keratoconus

Deep anterior lamellar keratoplasty on a previously failed full-thickness graft

PURPOSE

To report a case of deep anterior lamellar keratoplasty (DALK) on a previously failed full-thickness graft in a case of herpetic keratitis.

METHODS

A 70-year-old patient with a history of penetrating keratoplasty for herpetic keratitis performed 30 years ago presented with blurry vision in her left eye. She had corneal stromal scarring secondary to herpetic keratitis. The endothelium was spared. We performed a DALK with big-bubble technique.

RESULTS

Postoperatively, corneal edema was noticed initially, which resolved in 3 months. Her best-corrected visual acuity is 6/12 in her left eye.

CONCLUSION

DALK on a previous penetrating keratoplasty is a technical possibility when there is a functioning endothelium.

Comparison of three different techniques of corneal transplantation for keratoconus

PURPOSE

To compare the visual outcomes following deep anterior lamellar keratoplasty (DALK), penetrating keratoplasty (PK), and manual top-hat PK (TH-PK) in subjects undergoing corneal transplantation for keratoconus (KC).

DESIGN

A retrospective comparative case series.

METHODS

settings: Cornea clinic at the Toronto Western Hospital. study population: Fifty patients who underwent corneal transplantation for KC: 17 eyes underwent DALK, 20 eyes underwent traditional PK, and 13 had TH-PK. main outcome measures: Preoperative and postoperative uncorrected and best spectacle-corrected visual acuity (UCVA, BSCVA), high-order aberrations (HOA), complication rate, and endothelial cell counts.

RESULTS

The median BSCVA at 12 months follow-up was 20/40 in the DALK eyes and 20/30 in the traditional PK and TH-PK eyes. The mean final spherical equivalent power in the three groups was less than -1 diopter (D). The median astigmatism was less than 3.5 D in the three groups. Complication rates were similar for three groups, although the DALK group tended toward more complications. Although DALK and TH-PK procedure results in significantly shorter time to suture removal (P < .01), they caused increased levels of HOAs (P = .02). Endothelial cell counts at 12 months were significantly higher in DALK and TH-PK eyes when compared to the traditional PK eyes (P < .001).

CONCLUSIONS

DALK, PK, and TH-PK provide comparable visual outcomes in keratoconus patients. Although DALK and TH-PK induce more HOA, they speed up the time to suture removal and provide higher endothelial cell density at one year of follow-up.

Intacs implantation using a femtosecond laser for management of keratoconus: Comparison of 306 cases in different stages

PURPOSE

To evaluate the efficacy of intrastromal ring segment (Intacs, Addition Technology, Inc.) implantation and analyze outcomes according to different keratoconus stages.

SETTING

Kudret Eye Hospital, Ankara, Turkey.

METHOD

In this retrospective noncomparative case series, 306 keratoconic eyes of 255 patients who had Intacs segment implantation were reviewed. Patients were grouped according to the Amsler-Krumeich keratoconus classification (stage II, 155 eyes; stage III, 83 eyes; stage IV, 68 eyes). The uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), central corneal curvature, spherical and cylindrical manifest refractions, and central corneal thickness were analyzed and compared according to keratoconus stage.

RESULTS

At a mean follow-up of 10.39 months +/- 5.04 (SD), the BCVA improved in 71.6% of eyes and the UCVA improved in 75.7% of eyes. The mean keratometry (K) decreased from 50.7 diopters (D) to 47.9 D (P<.05); the mean manifest spherical refraction, from -6.04 D to -3.09 D (P<.05); and the mean manifest cylindrical refraction, from -4.11 D to -3.82 D (P>.05). The changes in BCVA and manifest spherical and cylindrical refractions were not statistically different between the different keratoconus stages (P >.05). There was less change in UCVA and more improvement in the mean K value after Intacs treatment in stage IV than in the other stages (P<.05, analysis of variance).

CONCLUSIONS

Intacs treatment with a femtosecond laser was effective for management of keratoconus of all stages. Improvement in UCVA may be less in severe keratoconus than in moderate keratoconus.

Inadequate results for microkeratome-assisted additive stromal keratoplasty for management of keratoconus

PURPOSE

To evaluate a new automated technique--microkeratome-assisted additive stromal keratoplasty (MASK)--for the management of keratoconus in eyes scheduled for surgery with clear cornea associated with total contact lens intolerance.

METHODS

This non-comparative, interventional case series included four eyes of four patients with stage I and II keratoconus associated with total contact lens intolerance. The first step of the surgical procedure consisted of performing a nasal-hinged flap on the host cornea with a microkeratome. The second step consisted of extracting a stromal piano-powered disk from the donor's cornea using an artificial chamber. The 80-microm thick lamellar graft was punched with a 7.5-mm circular trephine and positioned beneath the flap. Corneal refractive surgery was scheduled for the end of the sixth postoperative month.

RESULTS

No corneal refractive surgery was performed after 6 months of follow-up. Only one eye gained five lines of best spectacle-corrected visual acuity (BSCVA). Among the other three eyes, two had unchanged BSCVA and one lost one line of BSCVA. At the end of surgery, mean corneal thickness was increased by 148.75 microm.

CONCLUSIONS

Microkeratome-assisted additive stromal keratoplasty appears to be a safe and straightforward surgical technique that preserves the host endothelium and avoids the need of an open-sky procedure. However, in our study, MASK is not considered as an alternative to penetrating or deep lamellar keratoplasty in the management of keratoconus with clear cornea because of imprecise anatomic and refractive outcomes.

Longterm results of deep lamellar keratoplasty using grafts with endothelium

PURPOSE

To report the longterm results of deep lamellar keratoplasty (DLK) using grafts with their own endothelia.

METHODS

Fourteen eyes of 14 patients underwent DLK using grafts with endothelium. The average follow-up was approximately 80.0 months. Preoperative diagnoses included: corneal leukoma (five eyes); gelatinous drop-like corneal dystrophy (three eyes); Avellino corneal dystrophy (two eyes); corneal perforation (two eyes); corneal mucopolysaccharidosis (one eye), and keratoconus (one eye).

RESULTS

Corrected visual acuity was improved in 13 eyes (93%), but ruptures of Descemet's membrane occurred in six eyes (43%) and a double anterior chamber was found in five eyes (36%) postoperatively. Despite this, all grafts remained clear as a result of their functioning endothelia.

CONCLUSIONS

Deep lamellar keratoplasty using a graft with its own endothelium is a safe and valuable procedure with flexibility and feasibility that should suit corneal surgeons of all levels.

Contrast sensitivity in deep anterior lamellar keratoplasty versus penetrating keratoplasty

PURPOSE

To compare the measurements of contrast sensitivity at a distance in patients submitted to penetrating keratoplasty versus patients submitted to deep anterior lamellar keratoplasty for keratoconus treatment.

METHODS

Contrast sensitivity of 15 subjects submitted to penetrating keratoplasty and 15 subjects submitted to deep anterior lamellar keratoplasty have been analyzed through the Functional Acuity Contrast Test (F.A.C.T) 301.

RESULTS

There was no statistically significant difference between the measurements for penetrating keratoplasty and deep anterior lamellar keratoplasty.

CONCLUSION

Contrast sensitivity was similar among the subjects submitted to penetrating keratoplasty and to deep anterior lamellar keratoplasty for keratoconus treatment.

Use of a "small-bubble technique" to increase the success of Anwar's "big-bubble technique" for deep lamellar keratoplasty with complete baring of Descemet's membrane

PURPOSE

To describe a quick and simple "small-bubble" technique to immediately determine the success of attaining complete Descemet's membrane (DM) separation from corneal stroma through Anwar's "big-bubble" technique of deep anterior lamellar keratoplasty (DALK) for complete stromal removal.

METHODS

A partial trephination was followed by a lamellar dissection of the anterior stroma. Deep stromal air injection was then attempted to achieve the big bubble to help separate the stroma from the DM. To confirm that a big bubble had been achieved, a small air bubble was injected into the anterior chamber (AC) through a limbal paracentesis. If the small bubble is then seen at the corneal periphery, it confirms that the big-bubble separation of DM was successful because the convex nature of the bubble will cause it to protrude posteriorly, forcing the small AC bubble to the periphery. If the small AC bubble is not seen in the corneal periphery, this means that it is present in the centre, beneath the opaque corneal stroma, and therefore the big bubble has not been achieved.

RESULTS

We used the small-bubble technique to confirm the presence of the big bubble in three (one keratoconus, one interstitial keratitis and one dense corneal scar) out of 41 patients who underwent DALK. The small-bubble technique confirmed that the big bubble was achieved in the eye of all three patients. Complete stromal removal with baring of the DM was achieved, and postoperatively all three eyes achieved best corrected vision of 6/6.

CONCLUSION

The small-bubble technique can be a useful surgical tool for corneal surgeons attempting lamellar keratoplasty using the big-bubble technique. It helps in confirming the separation of DM from the deep stroma, which is important in achieving total stromal replacement. It will help to make the transition to lamellar keratoplasty smoother, enhance corneal graft success and improve visual outcomes in patients.

Future Directions in Lamellar Corneal Transplantation

The concept of lamellar keratoplasty (LK) is that of targeted lamellar replacement of corneal tissue while retaining normal cornea. It involves replacing either anterior stroma [anterior lamellar keratoplasty (ALK)] or posterior replacement of deep stromal and endothelial layers [posterior lamellar keratoplasty (PLK) or endothelial keratoplasty]. Despite the distinct advantages of ALK surgery, penetrating keratoplasty (PK) remains the most common procedure-largely because lamellar surgery is more technically demanding and time consuming, and interface irregularity arising from manual lamellar dissection often results in suboptimal visual outcomes. Recent improvements of surgical technique and advances in instrumentation such as microkeratome-assisted lamellar transplantation have contributed to improved visual quality with LK surgery. Long-term graft survival rates and endothelial cell counts after PK continue to drop for many years after surgery, clearly showing the disadvantage of unnecessary replacement of healthy endothelium in anterior-stromal disorders. The aim of this review is to evaluate the shifting emphasis from penetrating to lamellar forms of corneal transplantation and to highlight some future directions in lamellar surgery including new techniques in both ALK and PLK and the use of microkeratomes and femtosecond lasers to enhance outcomes.

Deep Lamellar Keratoplasty in Keratoconus With Healed Hydrops

PURPOSE

To report a case of successful deep lamellar keratoplasty (DLK) in a patient with keratonous after healed hydrops.

METHODS

A 17-year-old boy underwent DLK for corneal scar secondary to healed hydrops in a case of keratoconus.

RESULTS

The graft was clear, with a postoperative best spectacle-corrected visual acuity of 20/20.

CONCLUSIONS

DLK may be a viable option in healed hydrops.

Deep Anterior Lamellar Keratoplasty for Post-LASIK Ectasia

PURPOSE

To describe 2 cases of post-laser in situ keratomileusis (LASIK) ectasia managed with deep anterior lamellar keratoplasty (DALK).

METHODS

Clinical findings, surgical interventions, and outcomes are reported. The surgical technique of DALK is described.

RESULTS

Two patients developed progressive loss of vision after LASIK surgery with enhancement procedure(s). Corneal ectasia was diagnosed on the basis of clinical findings, progressive central corneal thinning on pachymetry, and topographical changes with irregular astigmatism and inferior corneal steepening. Both patients underwent uneventful DALK surgery, in which the anterior 80% of the central corneal stroma was replaced by a donor button and sutured in place. The postoperative recovery was uneventful, except for mild interface haze in 1 case, which resolved within 2 weeks of surgery. However, 1 patient underwent additional surgery, including clear lens extraction with intraocular lens placement, astigmatic keratotomies, and photorefractive keratectomy (PRK) to achieve good unaided visual acuity. At last follow-up, at least 2 years after DALK, both patients were satisfied with their vision. Their uncorrected visual acuity (UCVA) was 20/60+ and 20/40- in their operated eyes, improving to 20/40+ and 20/30- with minimal refractive corrections. The grafts and lamellar interfaces were clear.

CONCLUSIONS

We believe that DALK should be considered as an alternative to penetrating keratoplasty for the surgical management of post-LASIK ectasia.

Impact of the descemet membrane perforation on surgical outcomes after deep lamellar keratoplasty

PURPOSE

To study the influence of the Descemet membrane (DM) perforations after deep lamellar keratoplasty (DLKP) on endothelial decompensation, endothelial density, visual acuity, and postoperative complications. The relationship between DM perforations and pseudoanterior chamber formation also was studied.

DESIGN

Retrospective study.

METHODS

Ninety-six consecutive eyes of 89 patients who underwent DLKP with and without DM perforation were studied. The eyes with DM perforation were divided further into two groups: macroperforation and microperforation. Main outcome measures included graft survival, postoperative pseudochamber formation, endothelial density, and best spectacle-corrected visual acuity (BSCVA).

RESULTS

Overall, 88 of 96 eyes (91.7%) had clear grafts. Endothelial decompensation developed in three eyes (13.0%) in the eyes with perforation, which was significantly higher than in the eyes without perforation (1.4%; P = .047). Postoperative pseudochamber formation was observed in 60.0% in the perforated eyes, which was significantly higher than that observed in the imperforated eyes (19.7%; P = .0003). In the eyes with perforation, mean endothelial cell density was significantly decreased compared with that of the imperforated eyes at three and six months after surgery (P = .0497 and P = .0002, respectively). Three months after surgery, BSCVA in the imperforated eyes was significantly better than that in the perforated eyes (P = .016). Eyes with macroperforation were more likely to develop both pseudochamber and endothelial decompensation than eyes with microperforation.

CONCLUSIONS

Perforation of DM adversely affected endothelial decompensation and endothelial density after DLKP, especially in cases where perforations were large.

Deep anterior lamellar keratoplasty in post-laser in situ keratomileusis keratectasia

We describe a technique using deep anterior lamellar keratoplasty (DALK) in 5 eyes that developed keratectasia after LASIK. The technique is based on surgical manipulation that allows visualization of the lamellar dissection depth using a posterior approach to reach the predescemetic space. The mirror effect, indentation effect, and folding effect were used to determine proximity to Descemet's membrane. The same diameter donor and recipient buttons were used to correct myopia. The donor button without Descemet's membrane was placed using 10-0 nylon sutures. No intraoperative or postoperative complications occurred. The mean best spectacle-corrected visual acuity changed from 0.16 diopter (D) +/- 0.05 (SD) (range 0.10 to 0.25 D) before DALK to 0.68 +/- 0.19 D (range 0.5 to 1.0 D) after DALK. Deep anterior lamellar keratoplasty may be a better alternative than penetrating keratoplasty for any pathology with healthy endothelium.

Acuité visuelle un et deux ans après kératoplastie transfixiante pour kératocône

PURPOSE

To quantify the visual outcome obtained in patients operated on for penetrating keratoplasty for keratoconus (KC) after 1 and 2 years.

PATIENTS

and methods: The files from consecutive keratoconus patients operated on for PKP after more than 2 years of follow-up were retrospectively studied. The demographic charts, the KC stage, and the surgical features were noted. The best corrected visual acuities (BSCVA) were analyzed at the initial examination and after 1 and 2 years of follow-up.

RESULTS

One hundred and two eyes from 98 patients were analyzed, including 83 grade 4 (81%) and 19 grade 3 (18%) cases of KC. The mean preoperative BSCVA was 0.08 on the decimal chart, which increased to 0.5 and 0.6 1 and 2 years after penetrating keratoplasty (p<0.001, respectively). The mean keratometric astigmatism was 3.80+/-2.9 D and 3.94+/-2.3 D for the grade 3 and 4 KC, respectively, after 1 year and 2.52+/-1.9 D and 3.34+/-2.2 D after 2 years (NS). At this time point, 81% of the eyes had less than 5 D astigmatism.

CONCLUSION

One and 2 years after penetrating keratoplasty, a mean BSCVA of 0.5 and 0.6 could reasonably be expected in keratoconus patients and three-quarters of patients can be expected to see better than 0.5 after 2 years.

No sutures corneal grafting--a novel use of overlay sutures and fibrin glue in Deep Anterior Lamellar Keratoplasty

PURPOSE

To describe a case where Deep Anterior Lamellar Keratoplasty (DLK) was performed using overlay sutures and fibrin glue alone, without the need to directly suture the corneal button.

METHODS

Deep Anterior Lamellar Keratoplasty was performed using a modified Melles technique on a 21-year-old patient who had stromal scarring secondary to severe infective keratitis. Overlay sutures and fibrin glue were used to secure the donor button and then a bandage contact lens was inserted. No sutures were required to directly suture the donor button to host tissue. All securing sutures were removed 4 weeks after the surgery. Six months post surgery, the graft was clear and the patient rehabilitated by wearing acceptable astigmatic spectacle correction.

RESULTS

The patients visual acuity in the affected eye was 6/12 wearing a spectacle prescription of -0.25/-3.25x160.

CONCLUSION

The use of overlay sutures and fibrin glue in DLK is a time efficient and effective technique. We propose that this technique may be used routinely in cases where donor corneal button appears to fit well in the stromal bed at the time of surgery, that is, where there is no disparity in the thickness of the donor button compared to the host bed.

Quality of vision and graft thickness in deep anterior lamellar and penetrating corneal allografts

PURPOSE

To compare visual function after deep anterior lamellar keratoplasty (DALK) with visual function after penetrating keratoplasty (PK) for keratoconus and correlate this with corneal thickness.

DESIGN

Retrospective case series.

METHODS

Twenty-three patients (32 eyes) with unilateral or bilateral DALK or PK for keratoconus were analyzed for visual quality after suture removal. Evaluation included measurement of visual acuity, contrast sensitivity, and higher order aberrations (HOAs) (WaveScan; Visx, Santa Clara, California, USA). Readings were performed with both spectacle and rigid contact lens correction of refractive error. Total and residual stromal thickness after DALK was measured using optical coherence tomography (OCT) and correlated to visual quality.

RESULTS

Eyes after PK had better visual acuity than eyes after DALK (P = .018). Subgroup analysis of DALK eyes revealed that the level of visual acuity was related to the thickness of residual recipient corneal stroma. Eyes with a recipient corneal bed thickness of <20 microm had visual acuities similar to eyes with a PK, whereas those with a recipient thickness of >80 microm had a significantly reduced visual acuity (P = .0009). Contrast sensitivity was similar in DALK and PK eyes. There was no significant difference in HOAs between eyes with DALK or PK.

CONCLUSIONS

These data suggest that the main parameter for good visual function after DALK for keratoconus is the thickness of residual recipient stromal bed. An eye with a DALK with a residual bed of <20 microm can achieve a similar visual result as a PK.

Femtosecond Laser Keratome Creation of Partial Thickness Donor Corneal Buttons for Lamellar Keratoplasty

PURPOSE

To evaluate the thickness and diameter accuracy of the IntraLase femtosecond laser in harvesting corneal discs for lamellar keratoplasty. The stromal bed quality of resected corneas was evaluated by scanning electron microscopy.

METHODS

Two IntraLase units were used to create corneal discs at 225-, 300-, 400-, and 500-microm thickness settings and 7-, 8-, 8.5-, and 9-mm diameter settings (n = 28). Achieved thickness was measured using a digital caliper and achieved diameter was measured using imaging software. Samples were preserved and processed for scanning electron microscopy to observe stromal bed quality.

RESULTS

On both units, the mean deviation from attempted thickness was -9.5 +/- 8.6 microm (range: +6 to -28 microm). All of the obtained corneal discs were circular (horizontal versus vertical diameters, P > .05). The raster pattern produced a smoother stromal bed compared to the spiral pattern.

CONCLUSIONS

The IntraLase femtosecond laser keratome provides depth and diameter accuracy even at increased depth settings. Stromal bed was smooth with the raster pattern and can further be smoothed by excimer phototherapeutic keratectomy treatment. Femtosecond laser lamellar keratoplasty is a promising procedure and clinical data are needed to determine effectiveness.

Clinical outcomes after deep anterior lamellar keratoplasty using the big-bubble technique in patients with keratoconus

PURPOSE

To report clinical outcomes of deep anterior lamellar keratoplasty (DALK) using the big-bubble technique in patients with keratoconus.

DESIGN

Prospective noncomparative interventional study.

METHODS

SETTING

Single hospital.

PATIENTS

Eighty-one unselected consecutive patients with moderate to advanced keratoconus intolerant to contact lenses and with poor spectacle-corrected visual acuity.

INTERVENTION

DALK big-bubble technique.

MAIN OUTCOME MEASURES

Intraoperative and postoperative complications, postoperative uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction, corneal topography, and endothelial cell density.

RESULTS

Seventy-eight procedures (96%) were completed as DALK. Big-bubble was achieved in 50 cases (64%); 28 (36%) required manual intrastromal dissection. Intraoperative microperforations occurred in 11 cases (13%). Baseline mean uncorrected visual acuity was 20/500 and 20/60 two years after surgery. Average preoperative BSCVA, was 20/100 and 20/30 at the end of follow-up. Final BSCVA was better in patients in whom big-bubble with exposure of the Descemet membrane was achieved (P < .05). Average keratometry and SD (standard deviation) refraction changed from 62.1 +/- 6.7 diopters and -10.76 +/- 5 diopters to 47.51 +/- 4.73 diopters and -1.81 +/- 3.2 diopters, respectively after surgery. Mean preoperative endothelial cell density was 2202.29 +/- 392.35 cells/mm(2) and 2034 +/- 438.39 cells/mm(2) two years after surgery. Two patients developed stromal rejection.

CONCLUSIONS

The DALK big-bubble technique is a valuable treatment in patients with keratoconus. Visual outcome is comparable to standard penetrating keratoplasty (PK) when formation of big-bubble with exposure of the Descemet membrane (DM) was achieved. Clinically important graft-host interface developed in some cases after manual intrastromal dissection. Stromal rejection is a rare complication.

Deep Anterior Lamellar Keratoplasty (DALK)

PURPOSE

To review the visual outcome and complications of deep anterior lamellar keratoplasty (DALK), using Melles technique.

METHODS

All patients undergoing DALK between December 1999 and March 2005 were routinely entered into a longitudinal study. DALK was attempted in 80 eyes of 68 consecutive patients. Descemet membrane perforation occurred in 11 eyes, of which 7 required conversion to penetrating keratoplasty. The visual and refractive outcome of these eyes is presented separately. The mean follow-up was 21.2 months. Best-corrected visual acuities (BCVAs), refraction, graft clarity, and complications were recorded at each visit and analyzed.

RESULTS

The mean patient age was 34.2 years. Keratoconus was the main indication for surgery (58 eyes), followed by herpes simplex keratitis (6 eyes), corneal stromal dystrophy (5 eyes), stem cell failure with scarring (2 eyes), corneal dermoid (1 eye), and corneal opacity (1 eye). The mean central corneal thickness changed from 0.42 +/- 0.07 mm preoperatively to 0.62 +/- 0.06 mm postoperatively. At latest follow-up, BCVA of 6/6 or better was present in 24.7%, 6/9 or better in 69.9%, and 6/12 or better in 84.9% of the eyes. The mean postoperative refractive cylinder was 3.31 +/- 2.59 D, and the mean spherical equivalent was -2.54 +/- 3.61 D; 52.2% of the eyes had a refractive cylinder less than +/-3 D and 49.3% of the eyes had a spherical equivalent less than +/-3 D. Rejection episodes occurred in 9.6% of the eyes but were successfully reversed in all eyes. Graft failure occurred in 1 eye with severe stem cell deficiency.

CONCLUSION

This is the largest series of DALK cases using the Melles technique in a variety of corneal lesions. Our results confirm the usefulness and safety of this procedure in conditions with no endothelial involvement. Graft rejection remains a significant complication but is associated with good recovery because the endothelium is spared.

Factors predicting unsuccessful big bubble deep lamellar anterior keratoplasty

PURPOSE

To evaluate the role of corneal structural resistance as a surgical failure factor in deep lamellar keratoplasty (DLK).

METHOD

A total of 10 eyes of 10 patients underwent DLK at the Ophthalmic Hospital in Rome. The big bubble technique was performed for deep stromal dissection by air injection. Seven patients were affected by advanced keratoconus and corneal thinning ranging from 441 to 235 microm. Two patients were affected by central corneal opacity from herpetic keratitis, and one patient suffered from corneal leucoma caused by bacterial keratitis. Clinical follow-up comprising final astigmatism and visual acuity findings were evaluated with a minimum follow-up of 12 weeks.

RESULTS

DLK was successfully performed in eight eyes, five of which were affected by moderate to advanced keratoconus and three by post-infective corneal opacity. In these patients preoperative ultrasonic pachymetry ranged between 441 and 287 microm. In the remaining two patients a perforation of the Descemet's membrane (DM) occurred while attempting to separate it from the overlying stroma by the big bubble technique, requiring a penetrating keratoplasty (PK) to be performed. In both cases preoperative ultrasonic pachymetry was below 250 microm. Both perforations occurred at a different site than the needle site and at the operative time of the big-bubble injection.

DISCUSSION

An ultrastructurally weakened DM may suffer a loss of resistance to a stressing force, becoming unable to tolerate the big bubble technique, and thus being perforated. Since the weakening of the DM is related to end-stage keratoconus corneal thinning, the preoperative corneal thickness rather than the surgeon's ability can play a major role in surgical failure of DLK. Our study reveals a very high risk of perforation of the DM when pre-operative total pachymetry is below limit of 250 microm.

Comparative cohort study of the outcomes of deep lamellar keratoplasty and penetrating keratoplasty for keratoconus

AIM

To compare the outcomes and complications of deep lamellar keratoplasty (DLK) and penetrating keratoplasty (PK) for keratoconus.

METHODS

A cohort of 20 consecutive PKs, for keratoconus, was compared with 20 consecutive DLKs, for keratoconus. The PKs were performed between June 2000 and July 2001, the DLKs between October 2001 and October 2002. Surgery was performed by one surgeon. Best-corrected visual acuities (BCVA), refraction and complications were recorded at the time of surgery, 6 and 12 months postoperatively. chi(2)-tests were used to compare visual acuity outcomes and independent t-tests in the analysis of astigmatism.

RESULTS

Groups were comparable for age, sex, and ethnicity. All PKs were uncomplicated. Two of the DLK group had microperforations of Descemet's membrane. There was no significant difference in the proportion of patients achieving 6/9 or better between the PK and DLK groups (85 vs 78%, P=0.54). PK patients were, however, more likely than the DLKs to achieve 6/6 at 1 year; 70% (14/20) of PKs compared to 22% of (4/18) DLKs (P=0.04). Astigmatism was significantly higher in the PKs compared to the DLKs (P=0.022). There were two cases of graft rejection in the PK group, while none in the DLKs.

CONCLUSIONS

This study confirms good visual results from both PK and DLK in keratoconus with similarly high percentages reaching 6/9 BCVA. DLK appears to cause less astigmatism and also has the advantage of no endothelial graft rejection. The apparent cost, however, is a reduction in the likelihood of achieving 6/6 BCVA.

Intacs insertion with the femtosecond laser for the management of keratoconus

PURPOSE

To assess the outcomes of intrastromal ring segment (Intacs, Addition Technology) implantation for keratoconus using the femtosecond laser.

SETTING

Kudret Eye Hospital, Ankara, Turkey.

METHODS

In a retrospective noncomparative case series, 118 eyes of 69 patients with keratoconus who had Intacs segments implanted with the femtosecond laser were evaluated. Preoperative and postoperative evaluations included slitlamp examination, uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), and mean keratometry values measured with the Pentacam Scheimpflug camera (Oculus Opticgerate GmbH). All parameters were assessed preoperatively and 1 year after Intacs implantation.

RESULTS

Intacs were successfully implanted in all eyes. At the end of the first postoperative year, 81.3% of eyes had improved UCVA and 73.7% had improved BCVA. The mean keratometry decreased from 51.56 diopters (D) to 47.66 D, and the mean refractive spherical equivalent decreased from -7.57 D to -3.72 D.

CONCLUSIONS

Intacs implantation with the femtosecond laser was safe and effective for the treatment of keratoconus. All parameters had improved by the 1-year follow-up.

Deep anterior lamellar keratoplasty

PURPOSE OF REVIEW

Recent advances in surgical technique have promoted a paradigm shift in the surgical treatment of corneal disease. Penetrating keratoplasty is now being replaced by various types of lamellar techniques that aim to replace damaged tissue only, while maintaining healthy tissue intact. This review focuses on recent advances in deep anterior lamellar keratoplasty.

RECENT FINDINGS

The concept of creating a deep lamellar bed for lamellar keratoplasty is not new, but exposing Descemet's membrane was a tedious, time consuming procedure. New techniques that use air and ophthalmic viscosurgical devices to directly expose Descemet's membrane have dramatically reduced surgery time, while improving the safety of performing surgery. The indications for deep anterior lamellar keratoplasty have expanded from keratoconus and hereditary dystrophies, to include severe ocular surface disease and cases following infection and corneal perforation.

SUMMARY

Deep anterior lamellar keratoplasty can be considered as the first choice of surgery for a wide range of corneal disease, with bullous keratopathy as the only absolute contraindication.

Deep lamellar keratoplasty by intracorneal dissection: a prospective clinical and confocal microscopic study

OBJECTIVE

To evaluate the clinical findings, visual outcomes, and confocal microscopic corneal features of a surgical technique for manual deep lamellar keratoplasty (DLKP) with intentional sparing of the most posterior stroma.

DESIGN

Noncomparative, prospective, 12-month interventional study.

PARTICIPANTS

Forty-six eyes of 45 patients who had corneal pathologic features without endothelial abnormalities and requiring corneal graft were treated by DLKP by manual stromal delamination. They were examined clinically after surgery and using in vivo confocal microscopy at 2 weeks and 1, 3, 6, and 12 months.

INTERVENTION

The surgical technique consisted of an intracorneal deep manual stromal dissection through a 4-mm limbal incision at 50 mum from Descemet's membrane (DM). After trephination, an endothelial free graft was sutured.

MAIN OUTCOME MEASURES

Topographic parameters, interface depth and reflectivity, and anterior and postinterface keratocyte density; visual acuity was correlated with these parameters.

RESULTS

Two eyes had rupture of the DM. Two eyes that had delayed epithelial healing because of graft override with stromal inflammation underwent a second surgery (penetrating keratoplasty). Mean uncorrected logarithm of the minimum angle of resolution (logMAR) uncorrected visual acuity and logMAR best-corrected visual acuity (BCVA) improved from preoperative values (1.342+/-0.239 and 0.923+/-0.226, respectively) to 0.421+/-0.122 and 0.104+/-0.068, respectively, at 12 months. Mean topographic astigmatism was 3.09+/-1.30 diopters (D) at 3 months after suture adjustment, and 2.87+/-0.92 D at 12 months after suture removal. Average interface depth was 64.2+/-6.7 microm at 15 days and showed no significant changes up to 12 months. Mean interface reflectivity was highest at 15 days (95.5+/-15.7 light reflectance units [LRU]) and showed a progressive decrease over time of 55.3+/-8.7 LRU at 12 months. A significant negative correlation was observed between BCVA and topographic astigmatism up to 1 month and between BCVA and interface reflectivity starting from 6 months after surgery.

CONCLUSIONS

Deep lamellar keratoplasty by intracorneal dissection provides visual and clinical results comparable with that of other DLKP techniques. Visual recovery is slow and progressive, taking up to 1 year. Confocal microscopy enables precise evaluation of corneal features, interface morphologic features, and reflectivity, demonstrating a negative correlation between interface reflectivity and BCVA showing that the progressive recovery over months of the interface transparency is correlated with the increase in visual acuity after 6 months.

Impact of new lamellar techniques of keratoplasty on eye bank activity

BACKGROUND

Deep anterior lamellar keratoplasty (DALK) has become an increasingly popular alternative to penetrating keratoplasty in patients with stromal corneal pathologies. The main advantages of DALK are: prevention of long-term endothelial loss, elimination of allograft reaction and short topical steroid treatment with lower risks of glaucoma, cataract and infection. Because this technique enables surgeons to use corneal grafts with low endothelial density, the aim of this paper was to determine whether this type of innovation has had a significant impact on eye bank activity.

METHODS

We reviewed our corneal graft activity over a 40-month period and assessed the proportion of deep lamellar and penetrating keratoplasties. During the same period, we also evaluated our eye bank activity and recorded the utilisation of grafts with endothelium abnormalities, which were only suitable for lamellar techniques.

RESULTS

Deep lamellar keratoplasty represented 29.8% (85 out of 285) of corneal transplantations. Forty-eight percent of all corneas stored at the local eye bank were unsuitable for penetrating keratoplasty; 36.6% of those were not suitable for endothelial deficiencies. Among these, 72.7% were used for DALK and 27.3% were rejected. This permitted a 24.5% increase in corneal grafting activity. In contrast, Descemet's membrane was removed at the time of surgery in 12% of corneas with healthy endothelium, which was used for deep lamellar keratoplasty.

CONCLUSIONS

Deep anterior lamellar keratoplasty development and close collaboration between eye banks and surgeons can induce a significant increase in corneal grafting. This could be a partial solution in countries confronted with corneal graft shortages.

Comparison of deep lamellar keratoplasty and penetrating keratoplasty for lattice and macular corneal dystrophies

PURPOSE

To compare the therapeutic outcomes after deep lamellar keratoplasty (DLKP) and penetrating keratoplasty (PKP) in patients with lattice corneal dystrophy (LCD) and macular corneal dystrophy (MCD).

DESIGN

Age-matched control study.

METHODS

We reviewed the clinical records of 84 eyes with LCD or MCD who had DLKP (41 eyes) or PKP (43 eyes). Primary pathology consisted of 60 eyes with LCD and 24 eyes with MCD. DLKP was performed by either removing stromal tissue gradually, or by viscodissection of Descemet's membrane. Graft clarity, best-corrected visual acuity (BCVA), endothelial density, and complications were compared between DLKP and PKP, as well as between LCD and MCD.

RESULTS

All 84 eyes showed a postoperative improvement in visual acuity. The median final BCVA was not significantly different between PKP and DLKP groups. Endothelial cell loss rates were similar for DLKP and PKP. While the MCD-DLKP group showed progressive decrease in endothelial density, this was not observed in the LCD-DLKP group after surgery. In the DLKP group, most of the complications occurred intraoperatively or in the early phase, whereas late phase complications such as endothelial rejection and secondary glaucoma were the main complications in the PKP group.

CONCLUSIONS

PKP is no longer an automatic choice for the surgical treatment for LCD and MCD; DLKP seems to be a safe alternative. While DLKP is a favorable method for LCD, MCD may not be a good candidate, as it might show progressive decrease in the corneal endothelium postoperatively.

Therapeutic deep lamellar keratoplasty for corneal perforations

OBJECTIVES/AIMS

Corneal perforation can be potentially blinding unless the integrity of the globe is restored quickly. Although penetrating keratoplasty (PK) may achieve this, it carries a high risk of endothelial rejection in inflamed eyes. Deep lamellar keratoplasty (DLK) may be an alternative option to PK in such eyes owing to its potential for a lower incidence of rejection. We report the efficacy of DLK in patients with corneal perforations.

PATIENTS AND METHODS

Four patients underwent layer-by-layer DLK for noninfective corneal perforation, after measures such as the use of a bandage contact lens, tissue adhesive, and conjunctival pedicle flap had failed. The preoperative visual acuity was hand movements in one patient, 1/60 in two, and 6/60 in one. All four had iris incarcerated within the corneal perforations. SF6 gas (three patients) and air (one patient) were injected into the anterior chamber at the end of surgery.

RESULTS

The integrity of the globe was restored in all four patients with an improvement in visual acuity (6/60 in one and 6/36 or better in three). The mean follow-up time was 7 months. All four patients had clear corneas 3 months postoperatively, apart from the area of the original perforation. There was no recurrence of ulceration or perforation.

CONCLUSION

DLK is a safe and effective therapeutic measure in the management of patients with corneal perforations acting to preserve the integrity of the globe and restore vision.

Deep Lamellar Keratoplasty in the Treatment of Keratoconus

PURPOSE

To present our experience with a series of patients treated with deep lamellar keratoplasty (DLK) for keratoconus (KC).

DESIGN

A single surgeon, prospective, consecutive series.

METHOD

The study included all patients with KC who underwent DLK between March 1999 and November 2003 at the Royal Adelaide Hospital. The parameters evaluated included patients' demographics, pre- and post-operative best corrected visual acuities, post-operative keratometry, and intra- and post-operative complications.

RESULTS

There were 22 patients (23 eyes); 10 females and 12 males, with a mean age of 35 +/- 13 years (median, 33.5; range, 17-73). The median follow-up period was 13 months (range 7-38). In 89% (16/18) of eyes which underwent DLK, and in which a visual acuity could be obtained, a best corrected visual acuity of at least 6/12 was recorded. There were two episodes of Descemet's membrane perforation (8.7%), in which the procedure was converted to penetrating keratoplasty without complications. One patient developed a double anterior chamber, which resolved spontaneously without consequences.

CONCLUSION

The visual outcomes and complication rates seen in our series are comparable to the recent published literature. Hence DLK can be considered as a suitable alternative to penetrating keratoplasty for the surgical treatment of KC.

Patterns of rejection after deep lamellar keratoplasty

PURPOSE

To describe 7 patients with keratoconus who underwent graft rejection after deep lamellar keratoplasty (DLK).

DESIGN

Retrospective case series and literature review.

PARTICIPANTS

Seven patients who underwent DLK for keratoconus between 1997 and 2001. These cases were compared with a previously reported case series of DLK for keratoconus between 1994 and 2001.

METHODS

The clinical records of patients with rejection after DLK for keratoconus were examined to obtain details of the surgery, the interval to the rejection episode and its treatment, best-corrected visual acuity (BCVA), and presence of potential risk factors for rejection. The clinical features and course of rejection were compared with reports of corneal graft rejection in the literature. Patient characteristics were compared with the reported series of patients who had DLK for keratoconus.

MAIN OUTCOME MEASURES

Final BCVA and number, type, and features of rejection episodes.

RESULTS

The mean age was 28 years, with a median follow-up of 40 months after DLK. Rejection occurred between 3 and 41 months postoperatively. Four patients were atopic, 4 had a penetrating keratoplasty in the fellow eye, and 1 had deep stromal vessels in the host cornea. Isolated epithelial rejection occurred in 1 patient and stromal rejection in 3 cases, and there were 3 cases of mixed stromal and epithelial rejection. Topical steroid therapy led to reversal of rejection in 5 cases. Two patients had progressive vascularization with graft failure and poor vision. The median final BCVA was 6/9 (range, 6/6-6/36).

CONCLUSIONS

Deep lamellar keratoplasty avoids the risk of endothelial rejection, but epithelial or stromal rejection may still occur. Recognition and appropriate treatment are needed to prevent graft failure with subsequent visual loss.

Résultats de la kératoplastie lamellaire profonde pré-descemétique dans la prise en charge du kératocône chirurgical, en comparaison avec la kératoplastie transfixiante

OBJECTIVE

To determine the advantages, safety, and accuracy of deep anterior lamellar keratoplasty (DLK) versus penetrating keratoplasty (PK) in terms of visual acuity, astigmatism, and endothelial preservation in corneal diseases with healthy endothelium. Of these candidates for keratoplasty, the study investigated keratoconus patients with no other ophthalmic abnormalities.

MATERIALS AND METHODS

This comparative nonrandomized retrospective study investigated 22 patients with keratoconus requiring surgery, who underwent keratoplasty in the Nantes University Hospital between 1 June 2002 and 1 January 2004. Ten DLK, ten PK and two PK converted DLK cases were analyzed. Follow-up at 2 weeks and at 3, 6, 9, and 18 months is reported for visual acuity, astigmatism, pachymetry, specular microscopy, and intraocular pressure (IOP). Data are compared before and after surgery at each follow-up date.

RESULTS

Preoperative visual acuity improved in both groups from 0.14+/-0.13 to 0.8+/-0.17 postoperatively. There was no significant difference between the two groups before and at each time after surgery for visual acuity and astigmatism (3.5+/-2 diopters in the PK group and 3+/-0.9 D in the DLK group). There was a statistical difference for IOP with two occurrences of increased IOP up to 30 mmHg in the PK group. Endothelial cell count analysis showed an immediate postoperative decrease of 10% in the DLK group (versus approximately 40% in the PK group), remaining rather stable the 1st year (-3.3%), although cell loss in the PK group declined up to 10% more at 18 months.

DISCUSSION

With no statistical difference between the two groups for visual acuity and astigmatism, DLK is effective. It is safer than PK in terms of IOP disturbance (leading cause of graft failure) and endothelial cell loss. DLK converted into PK (16%) showed the same profile as first-intention PK.

CONCLUSION

Despite very similar effectiveness, DLK in keratoconus surgery should be proposed rather than PK because it appears safer not only in the short term but also probably in the long term, with no risk of endothelial cell rejection.

Management of corneal ectasia and cataract following photorefractive keratectomy

A 42-year-old man was referred to our clinic 18 months after bilateral photorefractive keratectomy (PRK). He had been on topical prednisolone acetate for 12 months because of post-PRK grade 4 haze. On his first visit, visual acuity was limited to light perception in both eyes because of moderate haze, significant corneal ectasia, and a white cataract. A 2-step surgical approach was elected in both eyes. First, a deep anterior lamellar keratoplasty was performed. Six weeks later, phacoemulsification with intraocular lens implantation was performed. Compared with a triple procedure combining penetrating keratoplasty and cataract surgery in 1 stage, the 2-step approach may lower the risk for corneal graft rejection and reduce ametropia.

Contact Lens Fitting for Keratoconus After Intacs Placement

PURPOSE

To describe a patient with keratoconus who underwent Intacs surgery to one eye with an unsatisfactory result and refused to undergo an Intacs removal procedure.

METHODS

Case report.

RESULTS

The patient's eye was fitted with a soft contact lens for visual rehabilitation 5 months after Intacs placement.

CONCLUSIONS

Intacs, with the help of secondary refractive procedures or contact lenses, may still be considered as effective in postponing penetrating keratoplasty, even in patients with advanced keratoconus.

Results of deep lamellar keratoplasty using the big-bubble technique in patients with keratoconus

PURPOSE

To evaluate the efficacy of deep lamellar keratoplasty using the big-bubble technique in patients with keratoconus.

DESIGN

Interventional case series.

METHODS

Thirteen eyes of 12 patients (eight male and four female subjects) with moderate to advanced keratoconus and intolerance to contact lens wear were included in this study. Deep lamellar keratoplasty was performed by the intrastromal air injection technique. Full-thickness donor tissue devoid of Descemet membrane and endothelium was then sutured into place. Best-corrected visual acuity, refractive results, surgical technique, and complication rates were analyzed.

RESULTS

Big bubble was successfully achieved in nine eyes (69.2%). Average postoperative best-corrected visual acuity was 20/25 (range 20/50 to 20/20) at a mean follow-up of 5 months. Intraoperative microperforation of Descemet membrane occurred in two eyes (15.3%). Three eyes (23%) developed a steroid-induced increase in intraocular pressure, which responded to medical therapy.

CONCLUSIONS

Deep lamellar keratoplasty that uses the big-bubble technique is safe and effective in patients with keratoconus. Visual outcome is comparable to standard penetrating keratoplasty, without the risk of endothelial rejection.