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At least 19 recordsLinked to original sources
PubMed1990

[Non-freeze epikeratophakia (live epikeratophakia)].

Instruments for the production of non-freeze epikeratophakia lenticules allow the surgeon to produce his own live lenticules from -35 to +25 dptr using the Barraquer-Krumeich-Swinger set. 29 myopic cases differ to the refractive target plus/minus 15% and reach contact lens visual acuity values after 2-5 weeks. 58 consecutive cases off epikeratophakia correction of aphakia result between 5 and 15% of the target. Optimal visual acuity is generally reached between 4 and 8 weeks postop. In 6 cases the epikeratophakia lenticule had to be removed and replaced.

Aphakia, Postcataract↗
PubMed1989

Update on epikeratophakia in children.

Epikeratophakia continues to be an extremely attractive option for younger children with unilateral aphakia who are noncompliant users of contact lenses but who are young enough to benefit from amblyopia therapy. The epikeratophakia procedure is much safer than IOL implantation. The epikeratophakia tissue lens is especially useful for children with traumatic aphakia and corneal lacerations because the lens can strengthen and smooth the cornea as well as correct the aphakia. This allows much quicker rehabilitation than could be accomplished with contact lenses. The epikeratophakia procedure may be combined with a cataract extraction and should be in those children with acquired cataracts who demonstrate contact lens noncompliance in an office trial of contact lens insertion before operation. Epikeratophakia should be used with caution in neonates and young infants because of the rapid growth of the eye. Extended-wear contact lenses are a safer option for these children, and epikeratophakia can be performed as a secondary procedure if and when problems with contact lens compliance arise. Surface ocular problems such as uncontrolled dry eyes or severe blepharitis will continue to be incompatible with the survival of epikeratophakia tissue lenses. Children who are treated with high doses of radiation for orbital tumors such as rhabdomyosarcomas invariably develop radiation cataracts, which can occur before the onset of radiation keratitis. These children do not do well with epikeratophakia tissue lenses. Likewise, children with severe metabolic disturbances who are not healthy or gaining weight have a diminished chance of graft healing, as do children with poor vision in whom oculodigital autostimulation produces persistent epithelial defects, which prevent survival of the tissue lens.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

[Reepithelialization of keratolens in the wound healing process following epikeratophakia in rabbits].

Most of the complications of epikeratophakia are minor and can be treated successfully. However, approximately 5 to 10% of cases of epikeratophakia result in removal of keratolenses mainly because of the failure to reepithelialize or chronic epithelial defects. In this study, in order to solve this problem we investigated the process of reepithelialization of epikeratophakia in rabbits. Epikeratophakia was performed on rabbit corneas using cryolathed keratolens. Ten, 16, 45, 63 and 90 days after the operation, corneas were excised, labeled with 3H-thymidine and examined histologically using light and electron microscope and autoradiography. 10 to 16 days after the operation, keratolenses were reepithelialized with a very thin epithelium of one or two layers. Epithelium thickened gradually, but was still thinner than normal controls at day 90. At days 10 and 16, basal cells of the epithelium showed high activity of 3H-thymidine incorporation, suggesting active proliferation. After that the proliferating activity decreased gradually and was no longer seen at day 90. Electron microscopic examination revealed no desmosomes or interdigitation between epithelial cells and poorly developed hemidesmosomes between basal cells and basement membrane at day 10, immediately after reepithelialization. At day 90, the epithelium over the keratolens showed areas where the basement membrane was irregular and extensively interrupted. These results indicated that in epikeratophakia, reepithelialization, recovery of epithelial thickness, formation of differentiated desmosomes or hemidesmosomes and normalization of ultrastructural abnormalities took longer than reepithelialization of usual epithelial defects. These results may explain the reason for of clinical problems of chronic epithelial defects or failure of reepithelialization in epikeratophakia. It was suggested that one of the factors causing delayed reepithelialization in epikeratophakia might be the cryolathing process of the keratolenses.

Animals↗
PubMed1982

Secondary surgical procedures after epikeratophakia.

Five patients required secondary surgical procedures after receiving epikeratophakia grafts. A neonate underwent epikeratophakia in combination with extracapsular cataract extraction, followed one week later by peripheral iridectomy and nine months later by strabismus surgery. A 53-year-old male had surgery to correct retinal detachment 4-1/2 months after epikeratophakia surgery for the correction of aphakia. A five-year-old male had epikeratophakia after removal of a traumatic cataract; five weeks later, retinal detachment necessitated vitrectomy, 360 degrees buckle, and cyclocryotherapy. A 4-1/2-year-old female had epikeratophakia for aphakia, followed nine months later by strabismus surgery. A 38-year-old female with keratoconus received a plano epikeratophakia graft, in combination with an extracapsular cataract extraction and anterior vitrectomy, followed two weeks later by an Ocutome vitrectomy. In all cases, the epikeratophakia grafts and interfaces remained clear, and in four of the five patients in whom secondary procedures were successful, vision continued to improve with time.

Adult↗
PubMed1988

Contrast sensitivity after epikeratophakia.

Epikeratophakia is a rapidly evolving surgical procedure for the refractive correction of aphakia. Even when Snellen acuity after epikeratophakia is normal, patients often report a subjective degradation of the visual image through the surgically corrected eye. To further define visual performance in the patient with optically successful epikeratophakia, we examined contrast sensitivity in two patients surgically corrected for monocular aphakia. Contrast thresholds were measured over a range of spatial frequencies using both computer-generated sinusoidal gratings and a commercially available wall chart system. The eye with epikeratophakia in each case was compared with the opposite normal eye with comparable acuity. One patient was also tested prospectively in the same eye both before and after surgery. Data demonstrate a depression of the contrast sensitivity function in the middle and high spatial frequencies induced by the placement of an epikeratophakia lenticule when compared with the normal eye or contact lens-corrected, preoperative aphakic eye with comparable good acuity. These findings may explain the subjective experience of epikeratophakia patients.

Adult↗
PubMedDate not supplied

Long-term follow-up of pediatric epikeratophakia.

BACKGROUND: Epikeratophakia is a potentially reversible corneal surgical procedure that can correct refractive errors in children who are aphakic and poor candidates for intraocular lens implantation. The correction of aphakia in the pediatric population poses specific problems because of associated amblyopia. METHODS: The clinical records of 61 consecutive patients (82 eyes) treated for pediatric aphakia by epikeratophakia were reviewed retrospectively with a follow-up of 3 to 5 years. For the purpose of analysis, the patients were divided into seven groups. RESULTS: The overall success rate for epikeratophakia was 92%, but with repeated surgery, the patient success rate was 93%. The average refractive error at 1 year was + 0.10 diopters (D). At 1 year, 68% of eyes had a refraction within 1 D of emmetropia. In these growing eyes, we documented an average myopic shift of -0.40 D during 4 years. A myopic shift occurred in 30.2% and a hyperopic shift in 9.4% of eyes. Spectacle-corrected visual acuity at 3 years showed 36% of eyes seeing 20/40 or better. Visual acuity results in different groups varied with the timing of epikeratophakia, density of amblyopia and parents' ability to maintain the patching schedule. The most encouraging results came from the treatment of monocular traumatic cataracts. In this group, 31% achieved visual acuities of 20/40 or better and 85% achieved 20/100 or better at final examination. Those with incomplete congenital cataracts also showed favorable results: 39% achieved 20/40 or better at final examination. CONCLUSIONS: Follow-up of 3 to 5 years demonstrated that epikeratophakia can correct refractive errors safely and successfully in aphakic children, either as a primary procedure, or as a secondary procedure after cataract extraction.

Adolescent↗
PubMedDate not supplied

Traumatic aphakia treated with an iris prosthesis/intraocular lens or epikeratophakia.

OBJECTIVE: We retrospectively analyzed the visual results and postoperative complications associated with severely traumatized eyes in which aphakia was corrected with epikeratophakia or a sutured iris prosthesis/intraocular lens (IOL). METHODS: Fourteen eyes (14 patients) with traumatic aphakia and severe anterior segment complications were corrected either with epikeratophakia or a sutured iris prosthesis/IOL. All eyes lacked lens capsule or iris support for an IOL. The surgical technique of implanting an iris prosthesis/IOL employed transcleral suturing in the ciliary sulcus combined with penetrating keratoplasty. RESULTS: In the eight eyes treated with epikeratophakia, four (50%) had spectacle-corrected visual acuity of 20/40 or better. Almost all of these eyes lost one or two Snellen lines of baseline spectacle-corrected visual acuity. Few complications occurred after epikeratophakia; none were severe. Of six eyes with penetrating keratoplasty and a sutured iris prosthesis/IOL or a sutured posterior chamber IOL, two (33%) achieved a visual acuity of 20/40 or better. In the IOL group, severe complications occurred, including posterior dislocation of the lens and secondary glaucoma. CONCLUSIONS: The surgical correction of aphakia in severely traumatized eyes requires specialized surgical techniques. Epikeratophakia is a low-risk operation that can be performed in eyes in which an IOL is contraindicated. The iris prosthesis/IOL technique results in good cosmetic results; however, due to complications, this technique should be used with caution.

Adult↗
PubMed1981

Epikeratophakia: the surgical correction of aphakia. III. Preliminary results of a prospective clinical trial.

Epikeratophakia is a newly developed, investigational form of refractive corneal surgery for the correction of aphakic vision. The procedure involves the removal of the corneal epithelium from the recipient eye and the suturing of a prelathed lamellar donor corneal graft onto the surface of the recipient cornea. We initiated a prospective clinical trial of epikeratophakia in comparison with keratomileusis; however, only 14 patients were randomized between the two procedures, after which the protocol was modified to eliminate the keratomileusis procedure. subsequently, all patients who entered into the study underwent epikeratophakia. The limited comparative study showed that epikeratophakia was at least as effective as keratomileusis in terms of visual potential and visual recovery. The major problem encountered was undercorrection, which was largely eliminated by the use of donor tissue larger in diamter than the recipient bed. Three months postoperatively, five of seven patients undergoing epikeratophakia had 20/50 or better visual acuity with spectacle overcorrection.

Adolescent↗
PubMed1990

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.

Aphakia↗
PubMed1992

Physiologic analysis of corneal healing after epikeratophakia.

The evaluation of epithelial permeability, stromal transparency, and endothelial cell density is essential to determine the resumption of normal function in each corneal physiologic unit after refractive surgical procedures. The authors report the results of a prospective study conducted in 55 consecutive patients undergoing epikeratophakia using prelathed, lyophilized tissue lenses. Epithelial permeability was evaluated by means of fluorophotometry preoperatively and 1, 2, 4, 8, 12, 24, and 52 weeks after epikeratophakia. With few exceptions, Scheimpflug photography also was performed at the same examination times to assess stromal optical density. Endothelial cell counts were performed in each patient preoperatively and between 6 and 12 months postoperatively. The epithelial barrier function resumed normal values within 8 weeks after epikeratophakia. The optical density of both donor lenticule and recipient corneas was initially increased but returned to values comparable with those of unoperated corneas by 12 weeks postoperatively. Endothelial cell density was not affected by epikeratophakia. These results confirm the authors' preliminary observation that epikeratophakia allows a relatively quick recovery of normal corneal functions and should prompt investigators to demonstrate the safety of other refractive surgical procedures in a similar way.

Aged↗
PubMed1991

Keratocyte activity in wound healing after epikeratophakia in rabbits.

Epikeratophakia is a refractive surgical procedure for the correction of aphakia, high myopia, or keratoconus. To solve clinical problems associated with epikeratophakia, a basic knowledge of its postoperative healing process is needed. The authors investigated keratocyte activities, particularly cell proliferation and collagen synthesis, during wound healing after epikeratophakia in rabbits. Epikeratophakia was done on rabbit corneas with a homologous cryolathed keratolens. Ten, 16, 28, 45, 63, 90, 254, and 360 days after the operation, the corneas were excised, labeled with either 3H-thymidine (10 microCi/ml) or 3H-proline (10 microCi/ml) for 4 hr and examined histologically and by autoradiography. Keratocytes in keratolenses were killed during the freezing process. On postoperative day 10, a few keratocytes migrated to the edge of the keratolens from the host stroma. On days 16 and 28, keratocytes in the keratolens and host stroma near the junction between the host and the keratolens incorporated 3H-thymidine, suggesting active proliferation. The proliferating activity was no longer seen after day 45. The repopulation of keratocytes was almost complete on day 90 and gradually returned to normal through day 360. Keratocytes in the keratolens and host stroma beneath the keratolens showed a higher 3H-proline incorporation than the control from days 16-254 with the highest activity at around 4-9 weeks after surgery. These results suggest that remodeling of collagen fibers continues for a long postoperative period after epikeratophakia.

Animals↗
PubMed1990

[Epikeratophakia].

Since its introduction by Kaufman in 1979, epikeratophakia has been used successfully in several thousands of patients for the correction of refractive errors. With this technique the original curvature of the cornea is changed by suturing onto it a preshaped lenticule. Depending on the different types of refractive errors to be corrected, the tissue lens is a plus lens (aphakia, hyperopia), a minus lens (myopia), or a plano lens (keratoconus). Both prelated, lyophilized tissue lenses and freshly cut lenticules have been employed with good results. However, the simplicity of the surgical technique, as well as the possibility of rejection of fresh corneal tissue, has made use of the former type of epikeratophakia lenses much more common. The basic indication for epikeratophakia is the incapability of correcting refracting errors with conservative methods, such as glasses, contact lenses or, in cases of aphakia, intraocular lenses. The results obtained in a series of 71 patients who underwent epikeratophakia at our Institute compare favorably to those reported in the literature. Following are some of the factors we identified as being responsible for our improved results: (1) the performance of all surgical procedures by the same corneal surgeon; (2) a longer hospitalization period and thereby closer observation of all patients and possible detection of early complications; (3) long-term postoperative follow-up examinations of all patients by the operating surgeon. In summary, epikeratophakia has been shown to be a safe, effective and potentially reversible procedure for the correction of refractive errors.

Cornea↗
PubMedDate not supplied

The corneal topography of epikeratophakia.

Epikeratophakia is a surgical technique initially developed for the correction of aphakia, and later adapted for the correction of keratoconus and myopia. The concurrent development of color-coded computerized corneal topography has greatly assisted in the evolution of epikeratophakia. Corneal topography has demonstrated the importance of both accurate centration of the epikeratophakia lenticle over the visual axis and the size of the optical zone on the final refractive results. Corneal topographic changes associated with correction of aphakia are primarily the result of steepening of the anterior radius of curvature of the cornea, in contrast to myopic correction which results in flattening of the anterior cornea. Correction of keratoconus results from a physical compression of the cone thereby flattening both the anterior and posterior radii of curvature. Preoperative topography in patients with keratoconus permits the precise position and extent of both regular and irregular astigmatism mation may assist in designing the optimal lenticle size and amount of graft decentration necessary to achieve the maximal surgical effect. Corneal topographic mapping has also been helpful in the management of postoperative astigmatism following epikeratophakia. Topography identifies the location and extent of both regular and irregular astigmatism which assists in planning of both surgical and nonsurgical intervention. Corneal topographic mapping has also been extremely helpful in the management of postoperative astigmatism following epikeratophakia. Topography identifies the location and extent of both regular and irregular astigmatism which assists in planning of both surgical and nonsurgical intervention.

Adult↗
PubMed1997

Measurement of intraocular pressure after epikeratophakia.

AIMS: To assess the accuracy of three commonly used tonometers in eyes after epikeratophakia. METHODS: Five eye bank eyes with sutured epikeratophakia buttons were connected to a manometer and a pressure transducer. Intraocular pressure was adjusted in 5 mm Hg increments from 0 to 50 mm Hg. The intraocular pressure was measured at each increment using a Goldmann tonometer, a pneumatonometer, and a Tono-pen. RESULTS: The difference between the manometer (actual pressure) and the Goldmann tonometer ranged from -19 to +9 mm Hg (mean (SD) overestimation 2.6 (5.8) mm Hg). The pneumatonometer error ranged from -27.5 to +5.5 mm Hg (mean (SD) overestimation 4.7 (6.1) mm Hg), and for the Tono-pen the range was -18 to +11 mm Hg (mean (SD) overestimation 0.05 (7.9) mm Hg). The correlation coefficients for the three tonometers were 0.94, 0.92, and 0.87 for the Goldmann tonometer, pneumatonometer, and Tono-pen respectively. CONCLUSION: The Goldmann tonometer had the best correlation with the manometer in eye bank eyes with epikeratophakia (correlation coefficient 0.94), but none of the tonometers was accurate over the entire range of pressures tested. Detection of glaucoma in eyes with epikeratophakia cannot rely on tonometry alone, but requires examination of the optic nerve and visual field.

Case-Control Studies↗
PubMed1997

The preliminary report of epikeratophakia in the treatment of pediatric aphakia after traumatic cataract extraction.

PURPOSE: To study the role of epikeratophakia in treating pediatric unilateral aphakia after traumatic cataract extraction. METHODS: We performed epikeratophakia in 43 children to treat aphakia after traumatic cataract extraction, using the corneal lenses made by ourselves. The rehabilitation of the the postoperative vision and the prevention of amblyopia were observed with a mean follow-up period of 20 months. RESULTS: All the lenses remained transparent. Postoperatively, 31 cases (72.1%) achieved uncorrected visual acuities (V.A) over 0.2, 32 cases (74.4%) achieved corrected V.A over 0.4. Most of the cases achieved the best preoperative corrected V.A with spectacles of less than 3 diopters. No severe complication occurred. CONCLUSION: Epikeratophakia is predictable with quality lens and correct surgical technique. The result suggests that the epikeratophakia is one of the best treatment for the pediatric aphakia especially for those who are not optimal for IOL implantation.

Adolescent↗
PubMed1989

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.

Adolescent↗
PubMed1981

Epikeratophakia: the surgical correction of aphakia. II. Preliminary results in a non-human primate model.

We have developed a new form of refractive surgery, epikeratophakia, in which a disc of donor corneal tissue is lathed to a specific dioptric power and sutured on top of the recipient's cornea after the recipient epithelium has been removed. The optical correction obtained with epikeratophakia should be similar in quality to that of a contact lens, but would be permanent and would require no maintenance. A non-human primate model was used to test the predictability, stability, and clarity of epikeratophakia grafts. After surgery, the grafts did not always re-epithelialize readily; this problem has been solved with the use of a small, steep, soft bandage contact lens. For the nine month period of this study, the epikeratophakia grafts have remained clear and the curvatures of the anterior surfaces have remained constant. However, the actual visual potential of these grafts can be evaluated only by a controlled clinical study in humans.

Animals↗
PubMedDate not supplied

Epikeratophakia in children with traumatic cataracts.

Epikeratophakia provides a permanent optical correction for aphakia in children with congenital or traumatic cataracts; suturing the epikeratophakia graft onto the cornea eliminates the problems of contact lens or spectacle non-compliance in these young and generally uncooperative patients and provides tectonic support to scarred and irregular corneas. Eighteen children under the age of six years underwent epikeratophakia for the correction of aphakia after the removal of trauma-induced cataracts. Graft success rate was 88%; the average change in keratometry in the patients with successful grafts was 14.82 +/- 2.0 diopters. In the 13 patients eligible for visual acuity tabulation, preoperative acuities ranged from light perception to 20/200, and postoperative acuities ranged from hand motions to 20/30. Ten (77%) had acuities of 20/80 or better. Poor results in three patients with less than 20/200 acuities were likely the results of non-compliance with amblyopia therapy. Present work indicates that in cases of traumatic cataract, the epikeratophakia procedure facilitates amblyopia therapy and decreases the astigmatism in scarred and irregular corneas.

Cataract↗