Epikeratophakia using small-incision lenticule extraction lenticule addition combined with corneal crosslinking for keratoconus.

An 18-year-old man with keratoconus had epikeratophakia using small-incision lenticule extraction lenticule addition in the left eye, which had a minimum corneal thickness of 356 µm. Accelerated (45 mW/cm2) transepithelial corneal crosslinking was performed 1 month later. The patient was followed for 3 years postoperatively. Examinations included anterior segment optical coherence tomography (AS-OCT), uncorrected (UDVA) and corrected (CDVA) distance visual acuities, subjective refraction, and topographic changes. The UDVA in the left eye improved from 20/200 preoperatively to 20/63 postoperatively, and the CDVA improved from 20/125 to 20/40. The manifest refraction was -1.50 -5.25 × 110. Corneal topography showed that lenticule implantation increased the thickness of the central and midperipheral cornea, with a minimum corneal thickness of 470 µm. The mean keratometry and greatest posterior elevation values were stable from 3 months postoperatively forward. On AS-OCT, the lenticule remained transparent and was attached smoothly with a visible demarcation line.

Femtosecond Laser-Assisted Small Incision Endokeratophakia Using a Xenogeneic Lenticule in Rhesus Monkeys.

PURPOSE: To evaluate the feasibility and safety of xenogeneic endokeratophakia in rhesus monkeys and to explore the effects of a concave lenticule on refractive power. METHODS: Three adult New Zealand white rabbits and 6 healthy rhesus monkeys were used. The xenogenic concave grafts were created from the rabbits using a modified small incision lenticule extraction technique; after being cryopreserved in glycerol for 1 week, the grafts were implanted into the monkey recipient corneas. Spherical equivalent (SE), central corneal thickness, and keratometry curvature were assessed preoperatively, 1 week, 1, 4 and 6 months postoperatively. The quality of the xenogenic graft was also assessed by slit-lamp microscopy, in vivo confocal microscopy, and optical coherence tomography with anterior segment imaging. RESULTS: The graft appeared to be swollen a day after the operation but reduced considerably after a week. A trend of a lower refractive power (hyperopic shift) was demonstrated in relation to the SE after concave graft implantation. The mean SE increased from -0.60 ± 1.31 (median -0.69, interquartile range -1.00 to 0.50) preoperatively to 0.75 ± 1.27 (median 1.38, interquartile range -0.25 to 1.63) at 1 month postoperatively (P = 0.01). Central corneal thickness was significantly thicker each time after surgery compared with that recorded preoperatively (P < 0.01). The anterior and posterior interface between the graft and stroma was visible during the study. Corneal nerve regeneration was evident at 6 months postoperatively. The xenogeneic concave graft was stable and transparent at follow-up. Severe adverse events or evidence of a rejection response were not observed. CONCLUSIONS: Femtosecond laser-assisted small incision endokeratophakia using a xenogeneic corneal lenticule seems to be feasible and safe, which may provide a new method for myopia correction and keratoconus treatment.

Using Donor Lenticules Obtained Through SMILE for an Epikeratophakia Technique Combined With Phototherapeutic Keratectomy.

PURPOSE: To investigate the feasibility, safety, and efficacy of using a donor lenticule created during small incision lenticule extraction (SMILE) in an epikeratophakia technique combined with phototherapeutic keratectomy (PTK). METHODS: Six patients with decreased visual acuity due to a recurrence of corneal dystrophy were included in this prospective pilot study. PTK was performed using the MEL 80 excimer laser (Carl Zeiss Meditec, Jena, Germany) followed by the transplantation of donor lenticules onto the recipient eyes. These lenticules were extracted during SMILE procedures using the VisuMax femtosecond laser (Carl Zeiss Meditec) on 6 donors with myopia and served as the epikeratophakia tissue. RESULTS: The surgeries and postoperative follow-up examinations were uneventful and no complications were noted over 6 months of follow-up. The epithelium remodelling was achieved within 1 month. At the last measurement, the corrected distance visual acuity of all recipient eyes gained at least two lines. Five eyes (83.3%) gained at least two lines of uncorrected distance visual acuity compared to their preoperative levels. Mean keratometric power increased by 5.97 ± 3.73 diopters and central corneal thickness increased by 55.25 ± 36.38 µm. The epithelium healed and the lenticules remained clear over the follow-up period as observed under slit-lamp examination. Anterior segment optical coherence tomography observation showed the lenticule was transparent with a visible demarcation line during the follow-up examination. CONCLUSIONS: The use of a SMILE lenticule as a donor lenticule for an epikeratophakia technique appears feasible and safe in the short term. The predictability and long-term effects need further investigation. [J Refract Surg. 2016;32(12):840-845.].

Anatomical and functional graft survival, 10 years after epikeratoplasty in keratoconus.

PURPOSE: To report outcomes of epikeratoplasty in keratoconus (KC), utilizing manually-prepared plano donor lenticules in terms of flattening of the cone, reduction in astigmatism and improvement in the visual acuity. MATERIALS AND METHODS: Patients with KC, having visual acuity <20/200, astigmatism >12 diopters (D) but without corneal opacity underwent epikeratoplasty, using manually prepared plano donor lenticules from fresh or M.K preserved corneas, between 1990 - 2000 and followed for 10 years, were included in this report. Visual acuity slit-lamp-biomicroscopy, keratometry, and refraction were performed at 8 weeks, 12 weeks, and 6 months for all 59 patients. The same were carried out at 1 year, 5 years, and 10 years depending upon the availability of the patient for that period. RESULTS: Of the 59 patients, only 26 were available for follow-up after 10 years. At 3 months, 1 year and 5 years, best corrected visual acuity of (BCVA) ≥20/60 were achieved in 84.7%, 84.4% and 80.3% of eyes, respectively. BCVA was 73% at 10-year follow- up, which was due to the presence of posterior subcapsular cataract (PSC). The average keratometric astigmatism and average flattening in diopters stabilized at the end of 3 months, which remained constant at 1, 5, and 10-year follow-up. The average diopter of myopia was stabilized by 1 year, which was almost same at 10 year. Graft was clear in all but 1 eye at 10 year follow-up. CONCLUSION: Epikeratoplasty is a useful technique for keratoconic eyes without apical scarring who fail or unable to use contact lenses.

Lamellar corneal transplantation.

Penetrating keratoplasty (PK) has been the gold standard for the surgical treatment of most corneal pathologies; lamellar keratoplasty that only replaces the diseased corneal layers has recently evolved as an alternative, however. Innovations in surgical technique and instrumentation provide visual outcomes comparable to PK. We review the indications and outcomes of various techniques of anterior lamellar surgery developed to treat stromal disorders. Similarly, we discuss posterior lamellar keratoplasty techniques such as Descemet stripping automated endothelial keratoplasty and Descemet membrane endothelial keratoplasty. Posterior lamellar keratoplasty provides faster visual rehabilitation than PK in cases of Fuchs endothelial dystrophy and pseudophakic bullous keratopathy. In addition, for medically unresponsive infectious keratitis, therapeutic anterior lamellar keratoplasty yields similar graft survival to PK without an increased risk of disease recurrence.

[Results of tectonic epikeratoplasty in the management of corneal perforations]. / Wyniki epikeratoplastyki tektonicznej w leczeniu perforacji rogówki.

PURPOSE: To present therapeutic application of tectonic epikeratoplasty as logical patch in severe ocular surface disorders. MATERIAL AND METHODS: Full thickness corneo-scleral transplants, 14 mm in diameter were used in 67 operations of 41 patients with corneal perforation or descemetocele. (14 women and 27 men), in the period 1998-2008. The mean age of patients was 55.2 +/- 17.7 years (range 15-82). The transplants were sutured over the limbus or the scleral rim and was implanted under the conjunctiva after 360 degrees peritomy. Donor tissue unsuitable for penetrating keratoplasty because of poor endothelium or corneal scarring, was obtained from Lublin Eye Bank. RESULTS: We observed closing of the perforation in all cases. Healing of the ulceration with scar formation and new vessels ingrowth was noted. In some eyes repeated epikeratoplasties were performed. CONCLUSIONS: Tectonic epikeratoplasty is a safe and simple method of treatment of corneal perforations. It provides a biological patch stimulating the healing of corneal defects. It gives time for systemic treatment before further ocular surface reconstructive procedures can be performed.

[Deep anterior lamellar (DALK) vs. penetrating keratoplasty (PKP): a clinical and statistical analysis]. / Tiefe lamelläre Keratoplastik vs. perforierende Keratoplastik: Klinische und statistische Analyse.

PURPOSE: Results of deep anterior lamellar keratoplasty (DALK) have been analysed regarding the BCVA, cylinder values, endothelial cell counts and complications both clinically and statistically. An answer to the question is sought as to whether DALK is an equal or better alternative to penetrating keratoplasty (PKP) given all indications with intact corneal endothelium. PATIENTS AND METHOD: A consecutive series on 166 eyes is compared to a group of 566 consecutive PKP eyes regarding visual acuity, astigmatism, stability of refraction and endothelial cell count. The operations were performed in one centre by the same surgeon with the same trephine (Guided Trephine System, GTS) and special instrumentation for DALK (Geuder, Heidelberg). All transplants were of a diameter of 8 mm, the fixation was done with the double-running antitorque suture with one exception. All cases of DALK and PKP were analysed first as two overall groups, then subgroups were broken down for keratoconus and endothelial cell counts (ECC). The subgroups comprised 135 DALK and 76 PKP eyes. RESULTS: BCVA was identical over the whole follow-up of 5 years for the overall groups of DALK and PKP. Statistically significant differences could only be found for the first 3 months favouring DALK (Median 0.5 to 0.35, p = 0.001), whereas for both groups BCVA was without statistically significant differences from month 6 through to 5 years. In the subgroups DALK versus PKP in keratoconus none of the medians from the 1st month to the 5th year were statically significantly different. Between the 1st and 2nd year a maximal BCVA of median 0.7 was reached. The analysis of the endothelial cell count shows both for the comparison of the overall groups and the subgroups keratoconus highly significant differences favouring DALK for all time intervals. CONCLUSION: Since stable ECC suggest an unlimited lifetime of DALK and there is no clinical difference in the outcomes of BCVA or cylinders it must be concluded that with the data presented the DALK operation should be preferred over PKP in eyes that preoperatively have normal endothelial cell counts.

[A preliminary report of epikeratophakia combined with two-stage photorefractive keratectomy in the treatment of keratoconus].

OBJECTIVE: To study the clinical results of epikeratophakia (EP) combined two-stage photorefractive keratectomy (PRK) in the treatment of keratoconus. METHODS: (1) Admission criteria for EP included: Best corrected visual acuity (BCVA) was no more than 0.3, keratoconus patients without scar in the central cornea could not tolerance the rigid gas permeable contact lens and corneal curvature was no more than 60.0 D. Criteria for the PRK included cornea astigmatism stable within 0.5 D for at least 3 months after EP, patient's age was 18 years or older, and absence of ocular disease, such as glaucoma or dry eye. (2) SURGICAL TREATMENT: EP surgery was performed and then followed by PRK at the second stage. (3) Postoperative follow up: Postoperative follow up included the examination of vision, corneal curvature, complications and immune rejection. RESULTS: Eight patients (10 eyes) received PRK after EP. BCVA was 0.3 - 0.5 in 1 eye and >or= 0.5 in 9 eyes in 12 - 18 months after EP. BCVA was >or= 0.5 in all eyes 12 months after PRK and 5 eyes obtained a BCVA of 1.0. The mean corneal astigmatism was (7.3 +/- 1.8) D before EP surgery, (3.8 +/- 1.6) D 12 - 18 months after EP, and (1.6 +/- 0.9) D after PRK. All grafts remained clear and no immune rejection was found after EP. 0.5 degree haze was observed in 1 eye, and no recurrence of keratoconus was found after PRK during the follow up period. COMPLICATIONS: secondary glaucoma (with disappearance of the anterior chamber) occurred in one eye 6 hours after EP surgery, and symptoms disappeared after reconstruction of the anterior chamber. The sutures were loosened in one cornea during the first 3 months after EP, it was corrected by resuture. CONCLUSION: EP combined with two-stage PRK is an effective method in treatment 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.

[Observation on healing process of corneal lens after epikeratophakia with confocal microscopy].

OBJECTIVE: To investigate the nerve and cell healing process of cryopreservation tissue lens after epikeratophakia by in vivo confocal microscopy. METHOD: Epithelia, stroma and nerves of tissue lens, interface between lens and recipient and stroma and endothelia of recipient were observed by in vivo confocal microscopy and recorded by video in 24 cases of keratoconus from 3 days to 5 years after epikeratophakia. RESULTS: Epithelial layer of lens: The tissue lens was covered by corneal superficial flat cells with wing cells and basal cells on the periphery at 3 - 4 days postoperatively, but the morphology and arrangement of these cells were irregular with low density. Superficial flat cells took shape completely at one month, and the morphology and density of the basal cells tended to be normal at 6 months postoperatively. Subepithelial nerve plexus were scattered at 18 months and their normalization completed at 2 years postoperatively. Stroma of lens: Keratocytes appeared circular, dot-shaped, rod-shaped or reticular in morphology postoperatively. Normal keratocytes were discovered sporadically on the periphery of the lens at 2 years postoperatively. At 5 years postoperatively the density of keratocytes was lower than normal stromal keratocyte in the center of the lens. Stromal nerves of lens: Nerves could grow into tissue lens at 6 months postoperatively, the quantity of nerves increased at 2 years and was still less than normal quantity at 5 years postoperatively. Stroma and endothelia of recipient: There was no change in the stroma and endothelia of recipient. CONCLUSIONS: There is significant difference among healing process of epithelia, nerves of unvital tissue lens after epikeratophakia, but there is little change in the transparency of tissue lens.

[Surgery for nearsightedness]. / Operation for naersynethed.

Myopia can today be reduced or eliminated by refractive surgery. Excimer laser surgery of the cornea by surface sculpturing (photorefractive keratectomy) or intrastromal tissue removal (LASIK) are the most widely used techniques, although implantation of intra corneal ring segments for low myopia also appears promising. Treatment of high myopia (> 10 diopters) is still difficult although epikeratoplasty or phakic IOL implantation are present possibilities. The perfect surgery for myopia remains to be developed, but the existing techniques will without doubt be further optimised. In 10 years time, supra normal visual acuity may even be obtained when surgical, optical, and biological variables can be described and controlled in each individual undergoing refractive surgery.

Non-freeze epikeratophakia in children.

We describe the use of unfrozen tissue lenses in 42 cases of epikeratophakia in children aged 2-14 years. Fourteen operations were performed in an aphakic eye, 28 in combination with congenital or traumatic cataract extraction. The tissue lenses, made from unfrozen donor cornea according to an original design, healed in 91.5% of cases. The tissue lens was removed when epithelial growth was inadequate on its surface. A five-year follow-up showed that correction within 3.0 D of emmetropia was achieved in 73.7% of the eyes. Preoperatively, mean keratometry readings were 43.5+/-0.2 D, increasing postoperatively to 53.6+/-0.8 D. Mean spherical equivalent at the spectacle plane increased by 9.6+/-0.9 D. Our investigations show the efficacy and safety of non-freeze epikeratophakia in the correction of pediatric aphakia.

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.

Autologous keratophakia for the correction of consecutive hyperopia after automated lamellar keratoplasty for myopia.

PURPOSE: Consecutive hyperopia occurs if too much corneal tissue is resected during automated lamellar keratoplasty for myopia. We report what are, to our knowledge, the first two cases of consecutive hyperopia after automated lamellar keratoplasty that were treated by keratophakia with autologous corneal tissue. METHODS: The patient in case 1 had a spherical equivalent refraction of +3.38 diopters (D) and the patient in case 2 a refraction of +3.63 D in each eye after automated lamellar keratoplasty for myopia. Corneal tissue from the contralateral eye of each patient was obtained with an automated microkeratome and transferred to the overcorrected eye in an autologous keratophakia procedure. RESULTS: The patient in case 1 had an unaided visual acuity of 20/20, with a spherical equivalent refraction of +0.63 D 4 months after the autologous keratophakia. The patient in case 2 had an unaided visual acuity of 20/60, with a spherical equivalent refraction of -2.25 D 2.5 months postoperatively. CONCLUSION: These two cases illustrate the use of simultaneous contralateral myopic automated lamellar keratoplasty with autologous keratophakia to treat eyes overcorrected following previous automated lamellar keratoplasty for myopia.

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.

[A study on neural regeneration after experimental epikeratophakia].

OBJECTIVE: To assess the effect of epikeratophakia (EKP) on corneal nerve regeneration and the recovery of corneal sensitivity. METHODS: 36 adult rabbits underwent epikeratophakia with either 0.2 mm or 0.3-0.35 mm circular trephination. A histochemical technique (acetylcholine esterase staining) was used to investigate the process of corneal nerve regeneration, and the recovery of corneal sensitivity was determined in 36 rabbits at various intervals after EKP. RESULTS: The corneal sensory nerves began to regenerate just peripheral to the host-donor interface 3 weeks following EKP, the nerve fibers traveled toward the stroma of the lenticules at 2 months, and formed a sparse subepithelial plexus at 8 months after surgery. A relative hyposthesia was found in the central zone of the lenticule when compared with its peripheral zone 4 months postoperatively. The sensitivity of the central zone remained lower at 5-8 months after EKP though it had remarkably increased. The density of re-innervated fibers was higher in the shallow incision than that in deeper one. CONCLUSION: It is suggested that the factors affecting the corneal innervation and the recovery of corneal sensitivity following EKP include; (1) the scar formation as a barrier; (2) the adaptation to the micro-environment around the lenticule; and (3) the depth of trephine cut. Therefore, a 0.2-0.25 mm depth of trephine incision is advantageous to the lamellar dissection, graft suturation and corneal nerve regeneration.

Long-term results of epikeratoplasty for keratoconus.

By analysis of outpatient records at the Massachusetts Eye and Ear Infirmary, the clinical course of 10 consecutive patients who underwent epikeratoplasty for keratoconus was reviewed to determine their clinical and functional status 5 years after surgery. Eight of 10 patients (80%) had clear, intact lenticules at 12 months. During a mean follow-up of 67 months (range = 35-101 months), each maintained long-term stability of best corrected vision, refractive astigmatism, and keratometric astigmatism. The mean uncorrected visual acuity improved from 20/660 to 20/134, whereas the mean spectacle corrected acuity improved from 20/260 to 20/30. All but one patient had a spectacle acuity equal to hard contact lens acuity. However, no patients were corrected to 20/20 at the end of the follow-up period. Refractive and keratometric astigmatism stabilized by 12 months (mean = 3.62 and 3.05 D, respectively), and decreased slightly during the longer period of follow-up (mean = 2.94 and 2.17 D, respectively). Epikeratoplasty is a useful method of visual rehabilitation in highly selected cases of keratoconus in which there is no central opacity, preoperative hard contact lens acuity is worse than 20/40, the average keratometry is < 60 D, contact lens intolerance is present, and in which the patient will tolerate some degree of reduced contrast sensitivity and < 20/20 high contrast acuity.

[Corneal reinnervation after lamellar keratoplasty in comparison with epikeratophakia and photorefractive keratectomy]. / Hornhautreinnervation nach lamellärer Keratoplastik im Vergleich zu Epikeratophakie und photorefraktiver Keratektomie.

Corneal sensitivity was examined with the Draeger aesthesiometer in 8 patients after lamellar keratoplasty, 7 patients after epikeratophakia and 82 patients after photorefractive keratectomy. We examined 9 different points in each cornea. The corneal sensitivity of patients after lamellar keratoplasty was normal 1 year after operation. A correlation with the depth of the lamellar dissection was demonstrated. Patients with lamellar keratoplasty with pterygium showed a sensitivity decrease in the nasal parts of the lenticule even after one year. Three years after epikeratophakia the corneal center was still not sensitive. After photorefractive keratectomy of more than 10 D, corneal hyposensitivity was shown even 2 years after operation.