On-lay lamellar keratoplasty for the treatment of keratoconus

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.

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.

Studies of intrastromal corneal ring segments for the correction of low to moderate myopic refractive errors

PURPOSE

Intrastromal corneal ring segments (ICRS) were investigated for safety and reliability in the correction of low to moderate myopic refractive errors.

METHODS

Initially, 74 patients with spherical equivalent refractive errors between -1.00 and -4.25 diopters (D) received the ICRS in 1 eye. After 6 months, 51 of these patients received the ICRS in the contralateral eye. The total number of eyes investigated was 125. The outcome measures were uncorrected and best-corrected visual acuity, predictability and stability of the refraction, refractive astigmatism, contrast sensitivity, and endothelial cell morphology.

RESULTS

The 89 eyes with 12-month follow-up showed significant improvement with uncorrected visual acuities of 20/16 or better in 37%, 20/20 or better in 62%, and 20/40 or better in 97%. Cycloplegic refraction spherical equivalents showed that 68% of the eyes were within +/- 0.50 D and 90% within +/- 1.00 D of the intended correction. Refractive stability was present by 3 months after the surgery. Only 1 patients had a loss greater than 2 lines or 10 letters of best spectacle-corrected visual acuity, but the patient's acuity was 20/20. Refractive cylinder, contrast sensitivity, and endothelial cell morphology were not adversely affected. The ICRS was removed from the eyes of 6 patients. Three removals were prompted by glare and double images occurring at night; 3 were for nonmedical reasons. All patients returned to within +/- 1.00 D of their preoperative refractive spherical equivalent, and no patients lost more than 1 line of best corrected visual acuity by 3 months after ICRS removal.

CONCLUSION

The ICRS safely and reliably corrects myopic refractive errors between -1.00 and -4.50 D.

Live-epikeratophakia for keratoconus

PURPOSE

To assess the clinical feasibility of refractive live-epikeratophakia (L-EPI) for early keratoconus to cap, rather than reverse, the ectatic cornea.

SETTING

Eye Department, Martin-Luther-Hospital, Bochum, Germany.

METHODS

Twenty-seven consecutive cases with keratoconus stage I-II had L-EPI. Lenticules were obtained from eye-bank eyes. The lenticules were cut on the artificial anterior chamber bench of the Barraquer-Krumeich-Swinger set. Optical power was generated over refractive dies to achieve postoperative emmetropia. The lenticule was sutured into a peripherally undermined 7.0 mm trephination with a double-running torque suture.

RESULTS

Re-epithelialization was complete within 4 to 6 days. In all but three cases that had corneal ulcers and experienced partial melting of tissue following severe neurodermatitis, all lenticules remained stable during the 10 year follow-up. The 1 month spherical equivalent remained almost stable over the entire follow-up. There was no sign of progression of keratoconus as induced myopia or astigmatism indicated by keratometry readings. Mean best spectacle-corrected visual acuity (BSCVA) was 0.45 (n = 27) preoperatively and 0.19 (n = 25) at 1 week, 0.39 (n = 26) at 1 month, 0.53 (n = 20) at 6 months, 0.58 (n = 13) at 1 year, and 0.64 (n = 8) at 2 years. Preoperative BCVA was achieved or improved in 13 eyes at 1 month. Postoperative astigmatism was < or = 3.25 diopters. Neither rejection nor lenticule opacification was observed.

CONCLUSIONS

Live-epikeratophakia is a safe and minimally invasive extraocular procedure suitable for keratoconus stage I-II. Progression of keratoconus may be arrested. If unsuccessful, the procedure is complementable and there is no interference with a later penetrating keratoplasty.

Epikeratoplasty for Keratoconus Using Manually Dissected Fresh Lenticules: 4-year Follow-up

BACKGROUND

Epikeratoplasty for keratoconus, in the absence of apical scarring, aims at reducing high irregular myopic astigmatism and provides an ectatic cornea with mechanical support.

METHODS

We performed epikeratoplasty on 11 keratoconic corneas using fresh or McCarey-Kaufman preserved, manually dissected donor lenticules. A disparity of 0.5 mm was maintained between the host and the donor. Patients with keratoconus having a preoperative spectacle-corrected visual acuity of less than 6/60 and intolerance to contact lens wear were included in this prospective study. Spectacle-corrected visual acuity, keratometry, and refraction were analyzed over a 4-year follow-up period.

RESULTS

Four year follow-up was completed on 10 eyes. Of these, 80% achieved a postoperative spectacle-corrected visual acuity of 6/12 or better. Average postoperative keratometry was 45.79 +/- 2.07 D and a decrease of 4.60 +/- 0.09 D was observed in refractive cylinder. Spherical equivalent showed a significant decrease in myopia of -4.35 +/- 0.26 D. Mean time to stabilization was 8 +/- 2.3 weeks. Epithelial defects occurred in three eyes; two were successfully treated by patching. One lenticule was removed due to graft infection following a persistent epithelial defect.

CONCLUSION

Epikeratoplasty for keratoconus is a useful procedure with good long-term visual acuity results and an early stabilizing period.

Management of perforations during epikeratoplasty for keratoconus

Epikeratoplasty (EKP) in keratoconus generally has few intraoperative complications. Perforations during EKP are rare but may force the surgeon to abandon the procedure. We developed a special suture technique to manage this problem. Several deep mattress sutures are placed by taking shallow bites of the central corneal rim and deep bites of the peripheral corneal rim. This leaves the peripheral corneal rim projecting forward by approximately one third the corneal thickness. Slight stretching of this peripheral corneal rim allows adaptation of the epilenticule to form a smooth tissue plane. This method was used in two patients with significant corneal scarring and led to satisfactory visual results.

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.

Epikeratophakia for keratoconus. Long-term results using fresh, free-hand made lamellar grafts

Epikeratophakia using fresh, free-hand made corneal grafts was done in 16 patients with keratoconus. The follow-up period averaged 27.8 months (range 13-45 months). A significant improvement of visual acuity was obtained (p = 0.002), and 14 of the 16 eyes (87.5%) achieved a corrected visual acuity greater than or equal to 6/12. The spherical equivalent and the cylindrical refractive error were reduced (p less than 0.05), and a significant flattening of the central corneal curvature was obtained (p less than 0.002). The mean postoperative central corneal astigmatism was 4.25 D. Postoperatively, the mean central corneal thickness was 0.670 mm, and the mean central thickness of the epithelialized graft was 0.336 mm. Six patients reported some postoperative glare or blurring of vision, despite a visual acuity greater than or equal to 6/9 on the Snellen chart. No significant subjective or objective changes were noticed after the 6-month postoperative follow-up visit.

Sclerokeratitis after keratoplasty in atopy

The authors report a series of five markedly atopic patients in whom a severe sclerokeratitis developed within 1 to 4 weeks of keratoplasty. The onset was acute with discomfort, photophobia, hyperemia, and mucus production. This resulted in early loosening of sutures and was associated with microbial keratitis in two cases and graft rejection in one. The inflammatory reaction was controlled with high-dose oral steroids and did not recur when the treatment was terminated. Serum IgE levels were elevated in all these patients (range, 421-8434 kU/l). Binding of this IgE onto the surface of mast cells in the conjunctiva with subsequent degranulation may be involved in the pathogenesis of the induced inflammation. Principal recommendations include the use of interrupted sutures and early immunosuppression with high-dose oral steroids at the onset of this condition together with the control of risk factors for microbial keratitis.

Penetrating keratoplasty for keratoconus in Down's syndrome

Five patients with Down's syndrome underwent penetrating keratoplasty for keratoconus. In three patients, the indication for surgery was acute corneal hydrops, which had not resolved in the three months before surgery. The other two patients had corneal scars. Two patients had combined penetrating keratoplasty, cataract extraction, and intraocular lens insertion. Four of the five patients maintained clear grafts at their most recent follow-up examination. Two of the five patients had one or more graft reaction episodes; one graft was lost. Good results can be obtained in penetrating keratoplasty for keratoconus in patients with Down's syndrome who do not demonstrate a tendency toward excessive eye rubbing and for whom a single observant caretaker can be relied on to provide consistent postoperative care.

One-year follow-up of epikeratophakia for keratoconus

We report 1-year follow-up findings on 42 of the first epikeratophakia procedures performed for keratoconus at the Helsinki University Central Hospital. Altogether 40 patients (42 eyes) received epikeratophakia grafts to flatten their cones. The age of the patients ranged between 19 and 44 years. The mean follow-up for these patients was 10.7 +/- 4.4 months, and in 12 patients follow-up extended to over 12 months. Overall, the success rate for the procedure was 93%, and with repeated surgery it was 97% for all patients; in all patients uncorrected visual acuity improved. Preoperatively 82% of the patients had uncorrected acuity worse than 20/400, while all patients followed for 1 year had uncorrected visual acuity better than 20/400. At 6 and 12 months postoperatively best corrected visual acuities were all returned to within one line of their preoperative best corrected acuity; in 83% acuities were 20/40 or better 12 months postoperatively. Four patients out of 12 followed for 1 year needed no postoperative overrefraction at all. The mean flattening by keratometry readings was 9.8 diopters (D) and the mean decrease in myopia in terms of spherical equivalent was 5.3 D. The degree of irregular astigmatism was measured in five cases using LSU topographical corneal shape analysis, and showed that the mean preoperative irregular astigmatism of 3.9 D was reduced to 1.3 D in the long-term analysis. One case report is presented to show in detail the topographical changes induced by epikeratophakia in keratoconus. The noninvasive nature of the epikeratophakia procedure makes it a safe and desirable option for the treatment of keratoconus.

Results of penetrating keratoplasty after epikeratophakia for keratoconus in the nationwide study

In the Nationwide Study of Epikeratophakia, 22 eyes underwent penetrating keratoplasty (PKP) after epikeratophakia for keratoconus. Reasons for PKP included visual acuity unsatisfactory to the patients (6 eyes), recipient corneal scarring (4 eyes), recipient Descemet's folds (3 eyes), scarring in the tissue lens (2 eyes), vascularization of the tissue lens (2 eyes), astigmatism (2 eyes), failure of the tissue lens to reepithelialize (1 eye), corneal ulcer (1 eye), and scarring of the donor and recipient cornea (1 eye). After PKP, all patients had clear grafts and 20/40 or better visual acuity. Average follow-up was 17 months. Three of the 22 patients (13.6%) had graft reaction episodes, all of which were treated successfully, resulting in clear grafts. The authors conclude that previous epikeratophakia does not adversely affect the outcome of subsequent PKP for keratoconus.

Epikeratophakia after ocular trauma

Five patients with long-standing monocular traumatic aphakia and contact lens intolerance underwent epikeratophakia. This procedure was chosen to rehabilitate the visual function in those eyes that exhibited distorted anterior segment anatomy after trauma. Three of the patients had corneal scars associated with their old perforation wounds, and all of them had undergone an intracapsular cataract extraction soon after their original injuries. Best-corrected visual acuity was 20/50 or better in all cases before surgery. Postoperative best-corrected visual acuity improved to within two lines of the best-corrected preoperative visual acuity, after a minimum follow-up period of six months. No intraoperative complications were noted. One cornea developed late-onset partial scarring of the interface in the area of the original scar, but the process arrested spontaneously.

Keratoconus: diagnosis and management

Keratoconus is a common condition whose clinical features represent a common effect on the cornea of a number of diverse processes. This review deals with the clinical signs and accompanying histological and biochemical changes within the cornea, evaluates the significance of associated ocular and systemic conditions and assesses the incidence and prevalence of the disorder. The wider ophthalmic community shares in the treatment of keratoconus, so the general principles of contact lens fitting associated with this difficult condition are examined and the specific protocol used at the Flinders Medical Centre is presented. When contact lenses are not tolerated or an adequate improvement in visual acuity is not achieved, surgery is the next option, so a full assessment is made of the risks and benefits of penetrating keratoplasty. Older techniques, such as thermokeratoplasty and lamellar keratoplasty, are examined and the new technique of epikeratophakia is evaluated.

Keratoconus. Evaluation of recent trends in the surgical and nonsurgical correction of keratoconus

Recent focus on the optical correction for "contact lens failure" keratoconus patients has been in the use of epikeratoplasty as an alternative to penetrating keratoplasty. In a 2-year retrospective review of keratoconus patients, 33 were referred as "contact lens failures" and as such might be considered candidates for surgical intervention. Of these, 29 patients (average keratometry, 50.4; range, 43-73) were successfully refitted with contact lenses. All patients obtained wearing times of 12 hours and achieved a visual acuity of 20/40 or better, with 85% realizing 20/30 or better. The data suggest that with concerted effort most keratoconus patients may be successfully refitted despite initial contact lens failure.

Indications and treatment of keratoconus using epikeratophakia

Nineteen patients with keratoconus underwent epikeratophakia by one of the authors (DSD) and were followed from 3 to 29 months. Patient selection criteria included contact lens failure, and minimal or no central corneal scarring. Uncorrected visual acuity improved by three or more Snellen lines in 13 of 19 patients (68%). Postoperatively, after more than 6 months follow-up, 81% of the patients had best-corrected visual acuity of 20/40 or better. A mean flattening of 4.73 diopters (D) occurred on keratometry readings. There was a mean decrease in refractive cylinder of 2.84 D. Spherical equivalent refraction showed a mean decrease in myopia of 4.64 D. Five patients had postoperative refractive cylinder greater than 4 D requiring relaxing incision(s). With some patients having been followed for more than 2 years, no recurrences of keratoconus have been noted. In properly selected patients, epikeratophakia can effectively be used to treat keratoconus and thus avoid potential intraocular surgical complications and immunogenic phenomena.

Epikeratoplasty. The surgical correction of aphakia, myopia, and keratoconus

Thirty-five patients have had 39 consecutive epikeratoplasty procedures (12 adult aphakic, 9 pediatric aphakic, 12 myopic, and 6 keratoconic eyes) by the same surgeon, using commercially prepared lenticules. The lenticule remained totally clear in 85% of eyes. Two lenticules were removed due to infection and scarring; four lenticules had minimal scarring and did not require removal. Spectacle-corrected acuity was worse than one line from the preoperative spectacle-corrected acuity in 58% of the adult aphakic eyes; however, 75% were 20/50 or better postoperatively. Fifty percent were within 2 diopters (D) of emmetropia and 92% within 3 D. All pediatric aphakic patients showed an improvement in best-corrected acuity, and 83% of eyes at 6 months were within 2 D of emmetropia; by 1 year a 3.4-D average myopic shift had occurred. Two of the six eyes (33%) using the original myopia technique were within 2 D of emmetropia, whereas five of the six eyes (83%) with the current technique are within this range. Spectacle-corrected acuity in the entire current myopia group has either improved by one or more lines or has remained unchanged. Five of the six keratoconic eyes had 20/40 or better spectacle-corrected and 20/25 contact lens-corrected acuity postoperatively; average corneal flattening was 6 D. Persistent epithelial defect and irregular astigmatism were the principal factors in delay in visual recovery.

The nationwide study of epikeratophakia for myopia

In the nationwide study of epikeratophakia, 116 ophthalmic surgeons performed 352 procedures for the correction of myopia; 256 of the eyes had 30 or more days of follow-up after suture removal. Of 204 eyes, 153 (75%) were within 30% of emmetropia after surgery. Of 208 eyes, 202 (97%) had postoperative best corrected visual acuity within two Snellen lines or better of their preoperative visual acuity. All but one patient improved uncorrected visual acuity. Of the 120 patients who equaled or improved their preoperative best corrected visual acuity, 116 (97%) were within two Snellen lines of their preoperative measurement between 30 and 60 days after suture removal. Corneal astigmatism changed from a preoperative mean (+/- S.D.) of 1.4 +/- 0.8 diopters to a postoperative mean of 2.6 +/- 2.1 diopters. Of 352 tissue lenses, 36 (10%) were removed, largely as a result of inaccurate power, decay, or failure to reepithelialize, and 17 of these eyes underwent a second successful epikeratophakia procedure.

The nationwide study of epikeratophakia for aphakia in children

In the nationwide study of epikeratophakia, 97 surgeons performed a total of 335 procedures in 314 eyes for the correction of aphakia in children under the age of 8 years 1 month. Fifteen children underwent bilateral surgery. Thirty-six tissue lenses were removed and 21 of these eyes underwent a second epikeratophakia procedure. Overall, the success rate for procedures was 89%, and with repeated surgery it was 95% for eyes. Seventy-three percent of the patients were within 3 diopters of emmetropia after surgery. Visual acuity results in patients able to provide verbal responses to the illiterate E, Allen card, or Snellen line chart testing showed improvement in most cases. The safety of epikeratophakia makes it a desirable option for the correction of aphakia in children who are spectacle or contact-lens intolerant, and the permanence of the correction eliminates the problem of optical noncompliance.

The nationwide study of epikeratophakia for aphakia in adults

In the nationwide study of epikeratophakia, 154 ophthalmic surgeons who had attended a training course performed 519 procedures for the correction of aphakia in adults: 310 of the eyes had 30 or more days of follow-up after suture removal. Of 229 eyes, 172 (75%) were within 3 diopters of emmetropia after surgery. Of 259 eyes, 245 (95%) demonstrated improved uncorrected visual acuity; 138 (53%) improved by four or more Snellen lines. Of 265 eyes, 209 (78%) achieved within two lines or improved their best corrected visual acuity. Of the 119 patients who achieved or improved their preoperative best corrected visual acuity, 110 (92%) were within two Snellen lines or better by 30 to 60 days after suture removal. Of the 127 patients with more than three months of follow-up after suture removal, 124 (98%) of those between 18 and 70 years of age but only 13 of 23 (54%) of those between 81 and 87 years of age achieved within two lines or better of their best corrected visual acuity. Corneal astigmatism measured by keratometry changed from a preoperative mean (+/- S.D.) of 2.1 +/- 1.8 diopters to a postoperative mean of 2.7 +/- 2.6 diopters. Of the 519 tissue lenses, 22 (4%) were removed, and one third of these patients underwent a second, successful epikeratophakia procedure.

Histological study of epikeratophakia tissue lenses for myopia removed from two patients

Epikeratophakia tissue lenses for the correction of myopia were removed from two patients as a result of postoperative complications such as stromal folds, complaints of glare, and decreased visual acuity. Light and electron microscopic analysis showed protrusions in Bowman's membrane and the anterior stroma corresponding to corneal folds that had been observed clinically. The epithelial cells in these areas contained many vacuolations and a thickened basement membrane. Hemidesmosomes were decreased in number. The tissue lenses had been cut 1.5 mm larger in diameter than the trephined recipient bed into which they were placed. Excess tissue lens material in the central area may have been thrown into folds by mechanical pressure, resulting in the histological changes, clinical signs, and optical distortion that necessitated removal of these grafts. Recently, the surgical technique has been modified, in an attempt to eliminate this problem.

Five year follow-up of epikeratophakia in children

Epikeratophakia alters the anterior curvature of the cornea by the addition of a machine-carved donor lenticule. Since March 1980, 88 patients under eight years of age have had epikeratophakia, with at least six months of follow-up. Eighty percent of the original surgeries were successful; some failed grafts were replaced successfully, so that in all, 89% of the patients had successful grafts. The average increase in curvature of the cornea was 14.7 diopters, and the average spectacle overcorrection was +0.56 diopters. In these growing eyes, we documented a myopic shift of 1.5 diopters per year. Visual acuity results varied with the timing of refractive surgery, density of the amblyopia, and the parents' ability to maintain the patching schedule. The largest group of children were those who had unilateral traumatic cataracts. In this group, 7 of 15 patients who had surgery under 4 years of age had final verbal acuities of 20/40 or better. Long-term follow-up has demonstrated that epikeratophakia safely and successfully corrects refractive errors in aphakic children either as a primary procedure, or as a secondary procedure after cataract extraction.

Epikeratophakia for myopia correction

Epikeratophakia is based on the principles of the Barraquer refractive procedures, with modifications that simplify the surgical technique and eliminate the use of the microkeratome by placing the donor corneal tissue lens on the anterior surface of the cornea. Procedures developed to permit freeze-drying the preshaped lens for storage enable these lenses to be obtained from a central source, freeing the surgeon from the complexities of the computer and the cryolathe. The correction of theoretically unlimited amounts of myopia is possible with these lenses. In 12 eyes that underwent the final epikeratophakia procedure, the average desired correction achieved was 98%.

Epikeratophakia in children

Epikeratophakia was performed in 61 children for the correction of aphakia after the removal of unilateral congenital or traumatic cataracts; 51 patients (54 grafts) have more than 6 months follow-up. In the first 27 grafts, 8 (30%) failed, but in the last 27 grafts, only 2 (7%) failed, largely due to improved surgical and tissue handling techniques. The average increase in corneal refractive power for the early patients was 12.68 +/- 4.63 D with an average overrefraction of +0.45 +/- 5.60 D. The last half of the patients showed an average increase of 14.83 +/- 4.83 D, with an average overrefraction of -0.00 +/- 5.20 D. Visual acuity results in patients with traumatic cataracts have been the most satisfactory, with the majority of patients obtaining useful vision. It also appears that in patients with congenital cataracts, the younger the patient at the time of surgery, the greater the chance for a good visual result. Some improvement in vision has been seen in all of the children with successful grafts, even those beyond the age when amblyopia therapy would be considered to have some potential for therapeutic effect. By attaching the correction permanently on the eye, epikeratophakia facilitates the vigorous occlusion therapy required after cataract extraction in these children.