Robert C. Arffa

Peripheral corneal disorders

The peripheral cornea is anatomically and physiologically distinct from its central counterpart. The major differences relate to the gradual transition of corneal tissues to those of the conjunctiva, episclera, and sclera; furthermore, the vascular structures, lymphatics, and inflammatory cells from these neighboring structures are intimately associated with the limbus and periphery of the cornea. The peripheral cornea is thereby predisposed to three main classes of disorders which do not normally involve the central cornea. First, local conditions affecting the sclera and conjunctiva may secondarily spread to involve the limbus and peripheral cornea. These include several infectious diseases, as well as hypersensitivity conditions, mass lesions, and degenerations. Second, due to the associated blood vessels and lymphatics, the peripheral cornea may be involved in a variety of systemic diseases, including vasculitides, autoimmune disorders, and abnormal metabolic conditions. Finally, there are several conditions, such as the noninflammatory peripheral degenerations, which primarily affect the peripheral cornea without associated ocular or systemic changes. In this review, we present a classification and discussion of the various disorders which may involve the peripheral cornea.

Intraocular Lens Removal During Penetrating Keratoplasty for Pseudophakic Bullous Keratopathy

Pseudophakic bullous keratopathy is now the most common reason for penetrating keratoplasty. In previous reports, the type of intraocular lens (IOL) most frequently encountered in these eyes was the iris plane IOL. The authors reviewed 27 cases of IOL removal during penetrating keratoplasty. Lenses were removed if they were dislocated or associated with iritis, recurrent hyphema, glaucoma, or persistent cystoid macular edema. The IOL encountered most often was the anterior chamber lens (in 22 eyes); closed thin loop, semiflexible or flexible anterior chamber lenses accounted for 19 of these. Iris plane lenses were removed from five eyes. No posterior chamber lenses were removed. Clear grafts were obtained in 24 of 27 cases (89%); visual acuity improved or remained the same in 24 cases, to 20/60 in 11 cases. The most common causes of poor postoperative vision were retinal disease (6/27 cases) and glaucoma (6/27 cases). The association between anterior chamber lenses and pseudophakic bullous keratopathy is probably the result of both the increase in use of these lenses and the documented propensity of the closed loop semiflexible anterior chamber lenses to cause complications.

Corneal Topography Using Rasterstereography

Rasterstereography is a new method of determining the topography of the cornea. Unlike Placido disc types of systems it does not depend on the reflectivity of the corneal surface, and it can provide information about the entire corneal, limbal and interpalpebral conjunctival surfaces. Since a smooth reflective surface is not required, images can be obtained with epithelial irregularity or defects, sutures, or stromal ulceration. A grid of horizontal and vertical bars of light is projected onto the cornea, and the pattern of the grid on the ocular surface is determined by its topography. The image is obtained by a video camera, and digitized, stored, and analyzed by an image processor. A three dimensional image of the corneal surface, contour maps of corneal elevation, and corneal curvature can be displayed.

Precarved Lyophilized Tissue for Lamellar Keratoplasty in Recurrent Pterygium

Thirteen eyes with recurrent pterygia were treated with excision and lamellar keratoplasty using precarved, lyophilized donor cornea. After an average follow-up of 23 months, only one eye (7.7%) required repeat excision. Two eyes (15.4%) had minor recurrences that were asymptomatic and did not progress. Minimal vascularization at the interface between donor and recipient cornea was frequent, but this completely regressed after suture removal and topical corticosteroid treatment. Limitation of movement, when present preoperatively, was improved or eliminated. Best corrected visual acuity was unchanged in eight eyes (61.5%), decreased by one line in two eyes (15.4%), and improved by one or two lines in three eyes (23.1%). Postoperative astigmatism was within 0.5 diopter of the preoperative value in 11 eyes (84.6%); one eye (7.7%) had a postoperative increase of 1 diopter and another eye (7.7%) of 2 diopters.

Calcofluor and Ink-Potassium Hydroxide Preparations for Identifying Fungi

Calcofluor and ink-potassium hydroxide preparations identified Fusarium solani, Aspergillus fumigatus, and Candida albicans, the three most common ocular fungal pathogens, in scrapings, biopsy specimens, and tissue sections of corneal mycotic infections in rabbits. These stains also identified fungal organisms in specimens from four human patients with keratomycoses. Neither procedure requires more than a few minutes to perform or extensive training or experience to interpret. The specimen stained with calcofluor can be examined immediately, but may not identify all fungi. The more sensitive ink-potassium hydroxide preparation should be examined after 18 to 24 hours, and is less likely to provide false-positive results than the calcofluor method.

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.

Results of a graded relaxing incision technique for post keratoplasty astigmatism.

A technique of graded relaxing incisions and compression sutures was performed for correction of post keratoplasty astigmatism in six patients who were spectacle and contact lens intolerant. Correction was achieved in all six patients after surgery, five with spectacles and one with a contact lens. Keratometric astigmatism decreased from an average of 9.63 diopters preoperatively to 2.17 D postoperatively, a reduction of 7.46 D, or 77%. Up to 13.50 D of correction was obtained. In general, the effect of surgery progressed from 1 week to 3 months postoperatively, and regressed from 3 to 6 months. Complications included perforation in two patients, one requiring suturing and application of tissue adhesive, and graft reaction in two patients. Although the number of patients is small, it appears that this technique can successfully reduce post keratoplasty astigmatism, even in excess of 10 D.

Combined Penetrating Keratoplasty, Extracapsular Cataract Extraction, and Posterior Chamber Intraocular Lens Implantation

We reviewed 22 cases of triple procedure in the last two years at our institution. Six months postoperatively 21 of the 22 transplanted corneas were clear. One graft for herpetic corneal scarring failed. Best corrected visual acuity was 20/40 or better in 14 patients. The average refractive error was--1.31 +/- 2.30 diopters. Refractive astigmatism was 4 diopters or less in 80% of patients. These results, which compare favorably with previous series, indicate the efficacy and safety of this procedure.

Prediction of Aphakic Refractive Error in Children

Formulas created to predict the optical requirements of the aphakic eye have been tested mainly in adult eyes. The accuracy of these formulas in shorter pediatric aphakic eyes was examined using retrospective analysis of 17 aphakic pediatric patients. The Sanders-Retzlaff-Kraff contact lens formula, used previously to predict required lens powers for epikeratophakia, consistently underestimated the required aphakic correction in the shorter eyes, which may have been responsible in part for the large undercorrections obtained previously in patients under one year of age. The Hoffer-Colenbrander and Binkhorst theoretical formulas, Donzis-Kastl-Gordon percentage change formula, and a linear regression formula derived from the present data (LIN), were significantly more accurate. The differences between these formulas were not significant. The use of one of these formulas should facilitate prediction of required epikeratophakia lenticule power or intraocular lens power in young children.

Deep suturing technique for penetrating keratoplasty

Purpose. To evaluate the effect of a new suturing technique on postkeratoplasty visual rehabilitation time and refractive error. Methods. Penetrating keratoplasty was performed on 17 eyes with keratoconus using a modified suturing technique. A donor button 8.0 mm in diameter was sutured into a 7.75-mm recipient bed with both deep and superficial sutures. The deep sutures consisted of either a single 16-bite 10-0 nylon running suture (n = 7) or eight interrupted 10-0 nylon cross-stitches (n = 10). These sutures were passed into the mid-stroma of the donor cornea and exited through the donor endothelium, then passed through the endothelium of the recipient cornea and exited from its mid-stroma. Thereby all parts of the deep sutures remained below the corneal surface. To further secure the surgical wound, in each case a running 16-bite 10-0 nylon superficial suture was also placed. Care was taken to maintain the bites of the superficial suture above the level of the deep sutures. The superficial suture was removed 3 months after surgery. Vision and refraction were recorded 1 day and 1 month postoperatively and 1 and 3 months after suture removal. A paired Student t test was used to verify the significance of changes in visual acuity and refraction recorded at different examination times. Results. As early as 1 month after surgery, spectacle best-corrected visual acuity 20/40 or more and refractive astigmatism less than 4 diopters (D) were recorded in each eye and maintained with two exceptions at the later examination times. In two patients, postoperative astigmatism increased from 4.5 to 5 D after suture removal. Conclusions. Deep suturing allowed quick visual rehabilitation while minimizing postkeratoplasty astigmatism in the patients with keratoconus operated on in this series.