The nationwide study of epikeratophakia for myopia

Corneal scarring from laser in situ keratomileusis after epikeratoplasty: clinical and histopathologic analysis

A 47-year-old woman required penetrating keratoplasty in the right eye after developing delayed visually significant corneal scarring bilaterally after laser in situ keratomileusis (LASIK) in 1997 following epikeratoplasty in 1987. Spectral domain ocular coherence tomography of the left cornea showed a 100 μm lenticule with a LASIK flap posterior to the host Bowman layer at 250 μm. Histopathology and electron microscopy of the right corneal button showed a 120 μm lenticule with a LASIK flap within the lenticule at 100 μm. Clinically significant scarring was present within the LASIK flap interface, within the lenticule stroma, and within the area of the underlying host Bowman layer. There were keratocytes at the junction between the LASIK flap and lenticule stromal bed. Although epikeratoplasty is no longer practiced, post-epikeratoplasty patients may present for refractive surgical options and LASIK carries significant risks for corneal scarring in these individuals, especially when using flap-creating devices that may create thin LASIK flaps.

Epikeratoplasty for adult and pediatric aphakia, myopia, and keratoconus: the Massachusetts Eye and Ear Infirmary experience

Between February, 1985 and February, 1987, 49 eyes of 47 patients underwent epikeratoplasty for one of the following indications: adult aphakia (21 eyes; 20 patients), pediatric aphakia (10 eyes; 10 patients), myopia (7 eyes; 6 patients), and keratoconus (11 eyes; 11 patients). Follow-up at least 12 months (average = 18 months) is available for all 49 eyes. Of 49 eyes, 44 (90%) were anatomically successful with an intact, clear lenticule at least 12 months post-operatively, with no significant difference between the four groups (adult aphakia = 90%, pediatric aphakia = 90%, myopia = 86%, and keratoconus = 91%). The functional success rate, however, was 91% for keratoconus, 81% for adult aphakia, 80% for pediatric aphakia, and only 43% for myopia. We conclude that epikeratoplasty can be an effective tool in the treatment of carefully selected patients with adult or pediatric aphakia and keratoconus, but has only limited applicability in the management of myopia.

Refractive surgery: through the looking glass

Historically, surgical procedures designed to change the refractive power of the cornea have been controversial at their inception, gaining acceptance only with time and study. From intraocular lenses to corneal remodelling with the excimer laser, and numerous procedures in between, including radial keratotomy, epikeratophakia, incisional keratotomy for astigmatism, and hydrogel and polysulfone implants, ophthalmologists have balanced the risks and benefits for their patients to produce the maximum benefit at the least cost. The present status and future potential of each of these are assessed as they appear today. There is no question that progress will continue, and that our patients will be the beneficiaries of our ongoing interest in improving older procedures and developing new techniques for the correction of refractive errors.

Long-term microstructural changes following epikeratophakia: in vivo confocal microscopy study

The unilateral epikeratophakic eye of a 20-year-old woman with a history of congenital cataracts was examined using laser scanning in vivo confocal microscopy 17 years after transplantation. In vivo confocal microscopy demonstrated a reduced keratocyte density in the grafted lenticule and the host stroma, with unusual elongated and tortuous hyperreflective branching structures in the anterior stroma of the host cornea. The sub-basal nerve plexus was present in the lenticule, although with a reduced nerve density. The appearance of the host endothelium was similar to that observed in Fuchs endothelial dystrophy. Dramatic microstructural changes were observed in almost all layers of the cornea 17 years after epikeratophakia. Although no longer performed as routine practice, in vivo confocal microscopy examination of epikeratophakia has provided fascinating insight into the potential corneal adaptations at a cellular level.

Histopathological and immunohistochemical studies of lenticules after epikeratoplasty for keratoconus

AIMS

To examine histopathological and immunohistochemical changes in lenticules and host of corneal buttons from patients who previously underwent epikeratoplasty for keratoconus.

METHODS

12 penetrating keratoplasty specimens from patients with keratoconus who had previously undergone epikeratoplasty, eight keratoconus, and seven normal corneas were examined. Immunostaining for Sp1, alpha1-proteinase inhibitor (alpha1-PI), and alpha2-macroglobulin (alpha2M) were performed.

RESULTS

In nine of the 12 lenticules, the keratoconus-like disruptions were found in Bowman's layer. Peripheral and posterior keratocyte repopulation of the lenticules was observed in all cases. Keratocyte repopulation in the anterior and mid-stromal regions of the lenticules appeared related to the time since epikeratoplasty. Sp1 nuclear staining of the basal and wing epithelial cells was more intense in lenticules and keratoconus corneas than in normal corneas. Lenticular, host, and keratoconus keratocytes showed positive Sp1 staining, whereas staining was absent in normal corneas. Compared to normal corneas, alpha1-PI and alpha2M immunostaining was lower in the lenticules, host, and keratoconus specimens.

CONCLUSIONS

The epithelial cells and keratocytes repopulated in the lenticules retain keratoconus-like biochemical abnormalities such as upregulation of Sp1 and downregulation of alpha1-PI and alpha2M. The authors speculate that both keratocytes and the corneal epithelium may participate in the development of keratoconus.

Ten-year follow-up of epikeratophakia for the correction of high myopia

OBJECTIVE

To determine the long-term functional results of epikeratophakia for myopic patients.

DESIGN

Retrospective, noncomparative, interventional case series.

PARTICIPANTS

Twenty-two patients (32 eyes; average age, 43+/-6 years) who underwent epikeratophakia surgery for high myopia. Mean preoperative myopia was -18.74+/-9.16 diopters (D; range, -7 D to -49 D). Follow-up was 12+/-2 years.

MAIN OUTCOME MEASURES

Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), change in mean keratometry, visual acuity under glare conditions, BCVA versus potential acuity meter reading, and patient satisfaction with the visual outcome.

RESULTS

Mean preoperative UCVA increased from 20/800+/-20/400 (range, counting fingers-20/400) to 20/80+/-20/200 (range, 20/250-20/32) in 24 eyes. Mean preoperative BCVA of 20/32+/-20/64 increased only in five eyes, whereas six eyes had no change and 18 eyes had a more than one line loss of Snellen BCVA. Mean preoperative keratometry reading decreased from 43.67+/-0.90 D (range, 41.0-46.25 D) to 37.40+/-2.92 D (range, 29.43-47.68 D). In the presence of glare, mean BCVA decreased to 20/100+/-20/100 (range, counting fingers-20/32). Potential acuity meter (PAM) readings were significantly (P<0.05) higher than BCVA. Mean PAM reading was 20/25+/-20/100 (range, 20/100-20/16). Seven patients (11 eyes) were extremely satisfied with the operative result more than 10 years after the operation, whereas four patients (four eyes) were not satisfied at all.

CONCLUSIONS

Epikeratophakia for the correction of myopia improved UCVA significantly, but BCVA decreased. The removal of the lenticules in patients who were not satisfied with their visual acuity was uncomplicated, and acceptable vision could be achieved with either contact lenses or intraocular lens implantation.

Corneal Sensitivity 10 Years After Epikeratoplasty

PURPOSE

To assess corneal sensitivity in patients 10 or more years after epikeratoplasty for myopia, aphakia, hyperopia, and keratoconus.

METHODS

A total of 45 eyes of 33 patients (age range at examination 33 to 55 yr) were included in the study. Corneal sensitivity thresholds using an electromagnetic aesthesiometer (Draeger) were measured at various locations on the lenticule and the recipient cornea. Measurements were evaluated regarding the corrective purpose, surgical technique, age, and gender of the patients and the area of measurements.

RESULTS

The mean corneal sensitivity threshold in the center of the epikeratoplasty lenticule was significantly lower than on the peripheral recipient cornea (320.0 +/- 365.1 x 10(-5) N versus 0.1 +/- 0.5 x 10(-5) N). Corneal sensitivity at the 3 and 9 o'clock positions was significantly higher compared to the values at the 6 and 12 o'clock positions on the lenticule. No correlations of these values with age, gender, type, and primary indications for the surgery were observed.

CONCLUSIONS

These results indicate a relative hypesthesia of the epikeratoplasty lenticule as compared to the peripheral host cornea, even 10 years after surgery. In our patients no clinically significant changes were observed that could be attributed to the reduced sensitivity over this follow-up period.

Advances in refractive surgery: 1975 to the present

PURPOSE

To review the major advances in the field of refractive surgery occurring over the past 25 years.

METHODS

Literature review.

RESULTS

The major developments in refractive surgery over the past 25 years are reviewed.

CONCLUSIONS

The past 25 years have witnessed great changes in refractive surgery. As a result of advancements in technology, instrumentation, and technique, we have seen improvements in the treatment of all types of ametropias. In this article, we review some of the successes and failures of the past quarter-century.

Long-term outcome of epikeratophakia

PURPOSE

To assess the long-term outcome of epikeratophakia.

SETTING

National center for pediatric ophthalmology (The Children's Hospital) and ophthalmology department in a regional general hospital (Waterford Regional Hospital), Republic of Ireland.

METHODS

A retrospective clinical review was carried out of 25 eyes (20 patients) with epikeratophakia performed over 10 years. Eyes were assigned to a children's group (Group 1) or an adult group (Group 2), depending on patient age at the time of surgery, and assessed with respect to indication for surgery, visual acuity, condition of the implanted lenticule, complications, refraction, and corneal topography. Histological analysis was performed on 1 removed lenticule.

RESULTS

Mean follow-up of all patients was 7.3 years (median 6.8 years; range 4.0 to 10.0 years). Most eyes (n = 18) were contact lens intolerant. Freeze-dried lenticules were implanted in all cases, and all but 1 had stable visual acuity from the early postoperative period to last follow-up. In Group 1 (n = 10), most eyes had a visual acuity of 6/36 or worse preoperatively with an improvement of 1 or more lines in 4 eyes. In Group 2 (n = 14), at last follow-up most eyes retained good or improved visual acuity by 1 or more lines. Most grafts were clear or had insignificant opacities outside the visual axis. The overall complication rate was 12%, with the most serious complication being significant induced astigmatism requiring removal of 1 epigraft. Mean induced astigmatism was 2.50 diopters (D) (median 2.00 D; range 1.00 to 6.00 D), which was accurately predicted within +/- 1.00 D by corneal topography in 14 of 19 eyes. Histology demonstrated infiltration of the implanted lenticule by host keratocytes.

CONCLUSION

Epikeratophakia, a reversible procedure with a low complication rate, resulted in stable visual acuity with good lenticule condition and minimal induced regular astigmatism after long-term follow-up.

Long-term results of clear lens extraction for severe myopia

PURPOSE

To evaluate the efficacy and safety of clear lens extraction in the management of severe myopia.

SETTING

Seoul National University Hospital, Seoul, Korea.

METHODS

This retrospective study comprised 24 eyes of 16 patients who had clear lens extraction to treat myopia of 12.00 diopters (D) or more. A scleral pocket incision and continuous curvilinear capsulorhexis were made followed by lens extraction by phacoemulsification and low-power posterior chamber intraocular lens implantation. Mean follow-up was 15 months.

RESULTS

Fifteen eyes (62.0%) were within 1.00 D of targeted refractive error postoperatively; 22 (91.7%) were within +2.00 D. Uncorrected visual acuity improved in all eyes. All except 1 (95.8%) gained two or more Snellen lines. Best corrected visual acuity improved in 20 eyes (83.3%); 15 (75.0%) gained two or more lines. Best corrected visual acuity after surgery was 20/40 or better in 19 eyes (79.2%), a 37.5% increase over the preoperative number. Posterior capsule opacification developed in 1 eye; a neodymium: YAG laser posterior capsulotomy was performed at 4 months postoperatively. No retinal breaks, retinal detachments, or cystoid macular edema were observed during the follow-up.

CONCLUSION

Clear lens extraction was effective in correcting severe myopia; however, longer follow-up of a large number of cases is needed to fully assess possible complications.

Viability of keratocytes in epikeratophakia lenticules

AIM

To study the influence of cryoprotectant, cooling rate, and warming rate on recovery and viability of keratocytes from corneas for cryolathing.

METHODS

Corneas were frozen at -50 degrees C for 2 minutes either after exposure to 10% dimethyl sulphoxide in Eagle's MEM for 15 minutes at room temperature (about 22 degrees C), or without earlier exposure to the cryoprotectant. Corneas were cooled either rapidly (20 degrees C/min) or slowly (1 degree C/min), and they were warmed either rapidly (> 50 degrees C/min) by direct transfer into medium at 22 degrees C or slowly (< 20 degrees C/min) in air at 22 degrees C. The cryoprotectant was removed by dilution in medium containing 0.5 mol/l sucrose. Recovery of keratocytes was determined by using collagenase digestion to release the cells from the stroma and trypan blue staining. Viability was assessed by the outgrowth of cells from stromal explants in primary tissue culture.

RESULTS

The use of a cryoprotectant before freezing was beneficial, irrespective of the different cooling and warming regimens. Both collagenase digestion and tissue culture revealed that keratocyte survival was improved when corneas were warmed rapidly rather than slowly. The collagenase digestion assay showed an apparently higher recovery of keratocytes after slow cooling (54.3%) than after rapid cooling (34.1%), but no differences in cell viability could be demonstrated by primary tissue culture.

CONCLUSION

Although in these experiments slow cooling apparently provided the best recovery of keratocyte numbers (though not viability), previous work had revealed some disruption of the epithelial basement membrane after slow cooling. If viable keratocytes and good preservation of epithelial basement membrane are considered to be prerequisites for epikeratophakia lenticules then it is suggested that corneas should be prepared for cryolathing by freezing rapidly after exposure to 10% dimethyl sulphoxide and, following cryolathing, they should be warmed rapidly.

Radial Keratotomy for Myopia From 5.00 to 13.00 Diopters Two Years After Surgery

BACKGROUND

Radial keratotomy for low myopia can produce good results with few side effects. For higher myopia, predictability becomes less accurate and side effects more common.

METHODS

A retrospective study of 111 eyes of 76 patients were divided into two groups. Group I had 79 eyes with myopia of -5.00 to -8.00 diopters (D); group II had 32 eyes with myopia -8.25 D to -13.00 D. One hundred eleven eyes were followed for 1 year and 90 eyes were followed for 2 years.

RESULTS

Sixty-seven (84.8%) eyes in group I and 12 (37.5%) eyes in group II achieved a refraction within the range of -1.00 D and +1.00 D. Ninety-two percent of group I and 44% of group II achieved an uncorrected visual acuity of 20/40 or better. Three percent lost spectacle-corrected visual acuity. Four eyes developed a hyperopic shift of 1.00 D or more between 2 months and 2 years. Seven other eyes developed a hyperopic shift of 1.00 D or more between 2 months and 5 years.

CONCLUSIONS

Eight-incision radial keratotomy is an attractive option for treatment of myopia up to -8.00 D. For levels above -8.00 D, the results are poorer; there may be a variable period before refraction stabilizes.

Epikeratoplasty for Myopia: 2-year Results and a Proposed Nomogram

BACKGROUND

Epikeratoplasty for myopia is a relatively safe and reversible surgical technique that can result in large refractive corrections. However, it is also claimed that long-term stability and predictability are not satisfactory due to refractive regression and undercorrection.

METHODS

In an effort to improve predictability and stability of epikeratoplasty for myopia, we followed 24 cases for 2 years and isolated factors affecting the postoperative refractive results.

RESULTS

We found that better refractive results were achieved at 24 months postoperatively for cases in which the power of preoperative myopia was lower. Our investigations also disclosed no significant correlation between the surgical outcome at 24 months and patients' sex, age, and preoperative keratometric readings.

CONCLUSION

On the basis of our observations, we propose a new nomogram where higher powers of minus keratolenses, compared to the traditional prescription chart, should be selected for those with high preoperative myopia to result in improved long-term results with epikeratoplasty for myopia. This nomogram has not yet been clinically tested.

Automated lamellar keratoplasty for the correction of hyperopia

Hyperopic automated lamellar keratoplasty (H-ALK) is a refractive procedure that corrects low to moderate hyperopia of up to +5.00 diopters (D). In this retrospective series, we examined the efficacy, predictability, and safety of H-ALK in 85 eyes in 49 patients. Follow-up was from 4 to 34 weeks (mean 18 weeks). Eyes were divided into three subsets: those in which we attempted an emmetropic result (n = 45), those in which we attempted to reduce, but not eliminate, hyperopia greater than 5.00 D (n = 23), and those in which we attempted a monovision result of -1.50 D (n = 17). In the eyes in which we attempted emmetropia, 76% achieved uncorrected visual acuity of 20/40 or better and 78.6% were within a range of -1.00 to +0.87 D. In those in which we attempted monovision, 47% achieved a spherical equivalent result between -2.50 and -1.00 D because of a tendency toward undercorrection. In those in which we attempted to reduce hyperopia, there was a mean correction of 4.33 D (standard deviation 1.36 D), with a range of 2.12 to 6.75 D. The most significant complication was a reduction in best corrected visual acuity of one to three lines in 11 of 85 eyes; this was transient in six eyes. These preliminary results compare favorably with those of other procedures to correct hyperopia.

Improved preservation of human corneal basement membrane following freezing of donor tissue for epikeratophakia

Current methods for the production of lenticules for epikeratophakia involve rapid freezing, cryolathing, and slow warming of the donor cornea. We have found that this procedure causes structural damage to the epithelial basement membrane in the donor cornea which may subsequently contribute to poor postoperative re-epithelialisation of the implant, leading to graft failure. Endeavouring to overcome these problems, the effects of cryoprotection of donor cornea were investigated, using dimethyl sulphoxide, in conjunction with different cooling and warming rates as part of the protocol for cryolathing. The structural integrity of the epithelial basement membrane zone (BMZ) was then assessed by electron microscopy and by immunofluorescence microscopy using antibodies to types IV and VII collagen, components of the basal lamina and anchoring fibrils respectively, and an antibody to a component of the anchoring filaments. No differences in the pattern of immunostaining for these components were detected, indicating that the composition of the BMZ was unaltered by the different treatment regimens applied. However, electron microscopy showed that preservation of basement membrane ultrastructure was markedly improved when cornea was warmed rapidly rather than slowly, both in cryoprotected and non-cryoprotected tissue. Epithelial cell retention and preservation of stromal architecture appeared superior in cryoprotected samples, while keratocyte structure was heterogeneous throughout the experimental groups. Further work is in progress to assess the efficacy of these protocols in the preservation of keratocyte viability in association with improved basement membrane structure in donor tissue for epikeratophakia.

Histopathological findings in failed human epikeratophakia lenticules

Six human epikeratophakia lenticules were removed 1 to 23 months after refractive keratoplasty for aphakia (n = 2) and myopia (n = 4). The myopic group included one epi-lenticule treated with ArF-excimer laser for hyperopia. Reasons for removal were epithelial defect (n = 4), edema of host cornea (n = 1), and overcorrection (n = 1). The epi-lenticule stroma showed centrally a regular fibrillar structure with a low keratocyte density. Electron microscopy (n = 1) revealed preserved cytoplasmic organelles and nuclear appearance. Mononuclear cells were absent. Polysaccharide was demonstrated in the stroma. Bowman's layer was normal without breaks. The epithelium had variable thickness. In the peripheral wound region stromal and epithelial irregularities were evident.

Clear lensectomy and implantation of low-power posterior chamber intraocular lens for the correction of high myopia

BACKGROUND

Although a variety of surgical procedures to treat high myopia have been studied, no consensus exists on the optimum procedure. Clear lensectomy with implantation of a posterior chamber intraocular lens has been regarded as risky, due to the higher incidence of retinal detachment in highly myopic eyes.

METHODS

The authors performed surgery and evaluation over 1 year in 52 eyes in which prophylactic retinal treatment, clear lensectomy, and posterior chamber intraocular lens implantation were used to treat high myopia of 12 diopters (D) or greater.

RESULTS

Before lens extraction, 31 eyes underwent argon laser photocoagulation. Over the 1-year period, three additional eyes were treated, and six eyes that had been treated preoperatively received additional treatment. No cystoid macular edema, retinal detachment, or persistent corneal edema was observed in this series. At 1 year, 88.5% of the group achieved corrected visual acuity of 20/40 or better, compared with 75% preoperatively. Uncorrected visual acuity of 20/100 or better was achieved by 84.6% of the group. The mean postoperative spherical equivalent was -0.86 +/- 0.84 D.

CONCLUSION

The refractive objectives were achieved. Complications reported previously with clear lensectomy were not experienced in this group. The low incidence of complications can be attributed to the short follow-up and probably in part to the prophylactic retinal treatment, combined with the phacoemulsification procedure for lens extraction. Longer follow-up is needed to fully assess the complications. Properly randomized prospective clinical trials will be able to fully assess the benefits and risks of prophylactic retinal treatment and clear lens extraction with posterior intraocular lens implantation. This series can help in evaluating this surgical procedure.

Epithelial interface cysts after epikeratophakia

BACKGROUND

Epithelial interface cysts have been occasionally observed after lamellar keratoplasty. The authors report the incidence, clinical significance, and management of this complication in epikeratophakia patients.

METHODS

From August 1987 to January 1991, 108 consecutive patients undergoing epikeratophakia entered a prospective study aimed at evaluating both clinical results and changes in corneal physiologic parameters. After an average hospitalization of 6 days, all patients underwent complete ophthalmologic examinations at regular intervals after surgery. All postoperative complications, including the development of epithelial interface cysts, were recorded and photographed.

RESULTS

Over a 3-year period, epithelial interface cysts were observed in 8 eyes, with an overall incidence of 7.4%. All cysts originated under the periphery of the epilens. In five patients, the cysts enlarged centripetally but eventually ceased to grow, causing no visual impairment. In two patients, after an initial increase in size the cysts slowly regressed and finally disappeared. In only one patient, a cyst migrated over the visual axis, thus necessitating surgical removal. The cyst did not recur during an observation time of 18 months after debridement, allowing full recovery of visual acuity.

CONCLUSION

The incidence of epithelial interface cysts after epikeratophakia is relatively high. Because of their peripheral location and self-limited growth, the clinical significance of this complication is low. The possibility of spontaneous regression of the cysts supports a conservative approach, as long as the visual axis is not affected. Surgical removal is possible without compromising the epi-lens and is compatible with an excellent visual outcome.

Long-term results of myopic epikeratoplasty

Twenty-three eyes of 20 patients who had had myopic epikeratoplasty were evaluated and the mean 21-month postoperative results (range: 12 to 47 months) tabulated. Average preoperative myopia was -16.7 diopters (D) spherical equivalent (range: -10 to -33 D), and average postoperative refractive correction was 13 D. Of 22 eyes, 17 eyes (77%) were within 4 D of emmetropia. Preoperative visual acuities without correction were between 2/200 and 20/100 (average = 2/40); postoperative acuities were between 2/200 and 20/20 (average = 20/40). Average preoperative best corrected visual acuity was 20/30. Best corrected visual acuities were unchanged or improved in 82% of cases. Re-epithelialization was complete within an average of seven days (range: three to 16 days) postoperatively except in one case in which the lenticule was removed because re-epithelialization did not occur. Five cases showed progressive loss of lenticular power.

Excimer laser refractive keratectomy for high myopia. 6-month follow-up of patients treated bilaterally

Both eyes of twenty patients were treated for myopia with refractive keratectomy using an excimer laser (193 nm), and followed for six months. The 40 eyes were divided into Group I (22 eyes) with an attempted refraction change of 5-8 diopters; and Group I (18 eyes) with 9-12 diopters of attempted refraction change. In Group I the corrected visual acuity improved or was unchanged in 16/22 eyes. Two eyes with high preoperative corrected visual acuity had experienced a significant loss in corrected visual acuity after 6 months. In Group II, the corrected visual acuity decreased in 10/18 eyes, in 4 eyes significantly. Among the 40 eyes, 39 had a refraction change less than intended after 6 months. Overcorrection was seen in only 1 eye. In Group I, 20/22 eyes were corrected up to 2.5 diopters less than attempted. In Group II, 9/18 eyes were more than 2.5 diopters from the attempted correction. All eyes developed subepithelial opacification ('haze'), which, in spite of steroid treatment, was still present after 6 months. The haze was more severe in eyes treated with 9-12 diopters of attempted refraction change. The achieved refraction change in the two eyes of the same patient was found to be correlated, possibly due to an individual factor in corneal wound healing.

Risk factors for complications following pediatric epikeratoplasty

We studied the prevalence and types of complications that occurred in children treated with epikeratoplasty to identify risk factors. A review of the clinical records of 88 consecutive patients (106 eyes; 114 procedures) revealed that no complications occurred in 58 grafts (54%). Refractive complications (refractive error greater than 3.00 diopters spherical equivalent from emmetropia or astigmatism greater than 3.00 diopters) occurred in 30 eyes (28%). Medical complications occurred in 22 eyes (19%); these included epithelial defects (14 grafts), interface opacities (six grafts), graft vascularization (eight grafts), graft infection (two grafts), graft necrosis (five grafts), graft haziness (four grafts) or opacification (11 grafts), and graft dehiscence (three grafts). Eleven grafts (10%) were removed and five eyes received new grafts. Epikeratoplasty in children will be more successful if risk factors such as patient age less than one year, microcornea, corneal endothelial cell dysfunction, mental retardation, and combining the procedure with cataract surgery are avoided.

Epikeratophakia for high myopia

A cryo-technique for production of corneal epi-lenses has been developed. During the manufacturing procedure the anterior surface of the tissue is moulded and the posterior surface cut with a microtome. After cutting, the epi-lenses are stored for days to weeks in an organ culture medium. Twelve eyes in 10 patients have been treated with epikeratophakia for high myopia (greater than -7 D). In all eyes, epithelialization was complete within one week, and at follow-up 3-18 months after the operation all epi-lenses were clear. The average refractive change in spherical equivalents was 9.7 +/- 4.4 D. All eyes obtained better uncorrected visual acuity, and no eyes lost more than one line of the best corrected visual acuity. At the time of follow-up, the patients' native cornea had regained normal hydration, whereas the epi-lenses did not thin as much as expected.

Visual performance after aphakic epikeratoplasty

While good visual acuity and refractive results after epikeratoplasty for aphakia have been reported, particularly for adults and older children, limited detailed information on the nature of the resulting vision is available. We have evaluated the visual performance of seven aphakic subjects corrected by epikeratoplasty by measuring contrast sensitivity, with and without the presence of glare. These results were compared with those for other aphakic corrections, namely spectacles (n = 5 eyes), contact lenses (n = 5 eyes), or intraocular lens implantation (n = 5 eyes). There were statistically significant differences among these four aphakic correction types (p = 0.0330), with a consistent trend for diminished visual performance after epikeratoplasty. Threshold elevations occurred in the presence of glare, but they were not statistically different between the groups (p = 0.1631). Based on these visual assessments, epikeratoplasty does result in statistically significant visual losses. Despite this, it may still offer an acceptable alternative to other managements of the aphakic patient when those others are contraindicated.

Bilateral phakic hypermetropic epikeratoplasty for accommodative esotropia

Optical correction of high hypermetropia with glasses is the primary treatment for accommodative esotropia. These glasses are often poorly accepted by adolescents and young adults for they are cosmetically undesirable, heavy, and esotropia occurs with their removal. We report an 11 1/2-year-old, physically mature female with high hypermetropia and accommodative esotropia corrected to orthophoria with glasses who was unable to be weaned from her glasses. She became intolerant to glasses wear, refused contact lenses, and was treated successfully with bilateral phakic hypermetropic epikeratoplasty. Two years postepikeratoplasty her visual acuity is 20/40 and 20/20 uncorrected and the vision in the amblyopic right eye has remained at its maximum preoperative level. She is orthophoric at distance and has a 2 prism diopter monofixational esophoria at near without glasses. Epikeratoplasty is an option in the treatment of accommodative esotropia for patients who are past the amblyopia forming age, have a stable angle of strabismus, and who require their full hypermetropic optical correction to maintain orthophoria.

Evaluation of functional and morphologic parameters of the cornea after epikeratophakia using prelathed, lyophilized tissue

Up to now, the attention of ophthalmic surgeons has been focused mainly on the clinical results of epikeratophakia, demonstrating its safety, relative predictability, and capability of correcting a wide range of refractive errors. However, no prospective study has ever been undertaken to evaluate the influence of epikeratophakia on various physiologic and morphologic parameters of the cornea. The authors investigated some of these parameters prospectively in eight consecutive patients undergoing epikeratophakia with prelathed, lyophilized tissue. Fluorophotometric evaluation of the epithelial barrier function, corneal densitometry by means of Scheimpflug photography, and endothelial specular microscopy were performed preoperatively and 2, 4, 8, 12, and 24 weeks after epikeratophakia. The epithelial barrier function was shown to return to normal 4 weeks after surgery. The optical density of both the epi-lenses and the host corneas increased early after surgery, but was comparable to that of unoperated corneas 6 weeks postoperatively in all cases but one. The endothelial cell density was not altered by surgery in any patient. Despite the limited number of patients, this study indicates that most functional and morphologic parameters of the cornea are normal as early as 6 weeks after epikeratophakia in most cases.

Epikeratophakia for aphakia, keratoconus, and myopia

A series of 67 cases of epikeratophakia is presented with an average time from surgery of 12.2 months. For aphakia there was a delay in the recovery of vision, but by nine months 83% of 57 patients achieved an acuity equal to, or within 1 line of, the preoperative value. 57% were corrected to within 3 dioptres of emmetropia, but in the latter part of the series 75% were within this range. Astigmatism and reduced contrast sensitivity, especially in the presence of glare, were important complications. For keratoconus, 86% of seven patients with over two months of follow-up achieved a spectacle corrected acuity of 6/9 or better. One patient had surgery for myopia and obtained the desired refractive correction.