Penetrating Keratoplasty Specimens Research Articles

CYSTEAMINE EYEDROPS DISSOLVE CORNEAL CRYSTALS IN YOUNG PATIENTS WITH NEPHROPAT11IC CYSTINOSIS

In nephropathic cystinosis, corneal cyatine crystals are present by one year of age and increase in density with time. The crystals are blamed for the photophobia and corneal erosions which plague older patients. He studied the safety and efficacy of eyedrops containing cysteamine, a cystine-depleting agent, in dissolving corneal crystals. First, cystinotic corneal stromal cells, cultured from a penetrating keratoplasty specimen, were depleted of 82% of their cystine by 1 mM cysteamine within 30 min. Second, rabbits treated for 8h per day for 3 weeks with 50 mM cysteamine eyedrops in a placebo-controlled, masked study exhibited no toxicity. Third, two cystinotic children (<2 years old) received cysteamine eyedrops (10 mM, hourly while awake) in a double-masked, placebo controlled trial. Normal saline was put in the opposite eye. In both children, biomicroscopic examination and silt lamp photography documented : a) Bilateral increase of crystals in the cornea between the start of oral cysteamine and the start of the eyedrop protocol; b) Nearly complete clearing of crystals from the cysteamine-treated corneas after 4-5 months of eyedrops; c) Progression or lack of regression in the corneas not treated with cysteamine. No toxicity was observed, and we are now treating the placebo eyes with cysteamine and enrolling older patients. This represents the first in vivo demonstration of crystal dissolution by cysteamine in cystinosis, and suggests that oral cysteamine, if adequately delivered to target tissues, might dissolve crystals in other cystinotic organs also.

Contact Lens Induced Keratopathy: A Severe Complication Extending the Spectrum of Keratoconjunctivitis in Contact Lens Wearers

A 21-year-old woman developed bilateral keratoconjunctivitis from contact lens wear, which progressed to diffuse corneal scarring and vascularization after the patient refused to discontinue wearing contact lenses. The visual disturbance became so severe that a penetrating keratoplasty had to be performed in one eye for visual rehabilitation. Examination of the penetrating keratoplasty specimen disclosed destruction of Bowman's membrane throughout the superior half of the cornea, which was replaced by a fibrous scar that was only mildly chronically inflamed. Deep vascularization occurred within the stroma. This case represents an extreme expression of a recently characterized syndrome consisting of conjunctival and corneal changes in patients who may be allergic to contact lenses or the solutions used in conjunction with their care. In the milder end of the spectrum, there is superior epibulbar conjunctival injection with associated tarsal injection, and a mild superficial punctate keratopathy without filaments. Some earlier workers have termed this syndrome a variant of superior limbic keratoconjunctivitis in association with contact lens wear, but this leads to confusion with Theodore's classical superior limbic keratoconjunctivitis, to which the present entity bears no etiologic relationship; it also fails to show many of the findings of Theodore's disease. In mild cases, we would recommend the term contact lens-induced keratoconjunctivitis, and in the more severe cases, such as demonstrated by our patient, we would suggest the term contact lens-induced keratopathy.

Keratophakia and Keratomileusis: Comparison of Pathologic Features in Penetrating Keratoplasty Specimens

Two patients, one who had had two keratophakia procedures, and another who had had a keratophakia, followed by a keratomileusis procedure both eventually required a penetrating keratoplasty. In the keratoplasty specimen bearing an intrastromal lenticle from a keratophakia procedure performed nine months earlier, no viable keratocytes were found in the in situ lenticle. The lenticle’s stroma stained paler with methylene blue and toluidine blue than the host’s surrounding stroma, probably due to the absence of proteoglycan synthesis. The interface scar between the lenticle and the host’s stroma displayed metabolically active keratocytes, amorphous basement membrane-like material, banded basement membrane material or long-spacing collagen of 1000 Å periodicity, microfibrillar collagen of 100 Å diameter, and, only in focal areas, more mature-appearing collagen of 200 Å diameter. In the keratomileusis-bearing penetrating keratoplasty specimen, complete repopulation of the keratomileusis’ stroma by the host’s keratocytes had been accomplished after seven months. The absence of any significant tinctorial differences between the keratomileusis’ stroma and the host’s stroma indicated that these keratocytes were functioning and able to produce proteoglycans. The interface scar between the keratomileusis’ stroma and the host’s stroma was similar to that in the keratophakia specimen, except for the lesser presence of mature collagen of 200 Å diameter. An explanation is not clearly obvious for the more rapid keratocytic repopulation of the keratomileusis’ stroma in comparison with the lenticle’s stroma in keratophakia. Both patients had successful penetrating keratoplasties, with postoperative visual acuities of 20/40 and 20/20, owing to the fact that the earlier corneal surgeries had not compromised the integrity of the anterior chamber structures.

Fibrous Ingrowth with Retrocorneal Membrane

A case of retrocorneal fibrous membrane is reported in a patient who underwent cataract extraction and experienced a postoperative hyphema. A distinctive straw-colored appearance to the membrane was due to blood staining. A penetrating keratoplasty with extensive anterior segment surgery restored the eye to useful vision. The penetrating keratoplasty specimen disclosed an unusual double-layered retrocorneal fibrous membrane, produced in part by a vascularized fibrous ingrowth and also by fibroblastic transformation of the corneal endothelial cells.

UNSUCCESSFUL PENETRATING KERATOPLASTIES. CORRELATION OF CLINICAL AND HISTOLOGIC FINDINGS.

During the past 15 years, 194 penetrating keratoplasty specimens have been seen at the Eye Pathology Laboratory of the University of California Medical Center, San Francisco. Of those 194 specimens, 40 met with the following three criteria: (1) Each was obtained from an eye that had had at least one prior unsuccessful penetrating keratoplasty. (2) In each case, the diameter of the second keratoplasty was larger than the first, indicating that the specimen represented an excisional biopsy. (3) Each case was one for which clinical and histologic data were available. These 40 cases form the basis for this report on the correlation of clinical and histologic findings of unsuccessful penetrating keratoplasties. The 40 patients were all operated on at the University of California Hospital, San Francisco, and their cases represent the techniques of several surgeons, including the resident staff. During the 15-year period covered in this report, there have been