Xeroderma pigmentosum and keratoconus

Outcomes of keratoplasty in a cohort of Indian patients with xeroderma pigmentosum

Purpose:

To evaluate the outcomes of keratoplasty for xeroderma pigmentosum (XP) performed at a tertiary eye care center.

Methods:

A retrospective review of medical records of those patients who were clinically diagnosed to have XP (54 eyes of 36 patients) and underwent keratoplasty; either deep anterior lamellar keratoplasty (DALK, four eyes), endothelial keratoplasty (EK, eight eyes), or penetrating keratoplasty (PK, 42 eyes) from 1994 to 2018.

Results:

The median age at surgery was 20.6 years (interquartile range [IQR], 14.6–27.6 years) and 20 (55.6%) were males. Graft failure occurred in 15 eyes (35.7%) in the PK group and two eyes (50%) in the DALK group; none failed in the EK group. The probability of graft survival in the PK group was 97.2% ± 2.7% at 1 year, 74.0% ± 8.0% at 2 years, and 54.8% ± 11.7% at 5 years. In the PK group, 13 eyes needed antiglaucoma medications, 11 eyes developed graft infiltrate, and 13 eyes needed secondary interventions (cataract surgery, excision biopsy, and tarsorrhaphy). In the EK group, three eyes needed secondary interventions (excision biopsy). Median postoperative endothelial cell density at the last follow-up in the PK group was 1214 cells/mm² (IQR, 623–2277 cells/mm²).

Conclusion:

Despite the complexities of the ocular surface and adnexal issues in XP, keratoplasty had reasonably good outcomes. More than half of the PK grafts survived 5 years with no failures in the EK group. Regular follow-up and timely management of suture-related infections raised intraocular pressure, and suspicious ocular surface lesions, in addition to solar protection, are important for the success of keratoplasty in these eyes.

Ophthalmic manifestations and histopathology of xeroderma pigmentosum: two clinicopathological cases and a review of the literature

Xeroderma pigmentosum is a rare, autosomal recessive disease caused by a defect in DNA repair. Patients with xeroderma pigmentosum often have cutaneous and ocular sun sensitivity, freckle-like skin pigmentation, multiple skin and eye cancers, and, in some patients, progressive neurodegeneration. Xeroderma pigmentosum predominantly affects the ultraviolet (UV) exposed ocular surface, resulting in eyelid atrophy and cancers, corneal dryness, exposure keratopathy, and conjunctival tumors. We report the clinical history and ocular pathology of two white women who had xeroderma pigmentosum with neurological degeneration: Case 1 (died at age 44 years) and Case 2 (died at age 45 years). Case 1, with mutations in the XPA gene, had more than 180 basal cell carcinomas of her skin and eyelids and died from complications of neurodegeneration. Case 2, with mutations in the XPD gene, was sun-protected and had three skin cancers. She died from complications of neurodegeneration and pneumonia. Both patients had bilateral pinguecula, corneal pannus, and exposure keratopathy. Case 1 had bilateral optic atrophy, and Case 2 had bilateral peripheral retinal pigmentary degeneration. Both patients developed retinal gliosis. The ophthalmic manifestations and pathology of xeroderma pigmentosum are discussed and reviewed with respect to this report and other cases in the literature. These cases illustrate the role of DNA repair in protection of the eyes from UV damage and neurodegeneration of the retina.

Keratoconus

Keratoconus is a bilateral noninflammatory corneal ectasia with an incidence of approximately 1 per 2,000 in the general population. It has well-described clinical signs, but early forms of the disease may go undetected unless the anterior corneal topography is studied. Early disease is now best detected with videokeratography. Classic histopathologic features include stromal thinning, iron deposition in the epithelial basement membrane, and breaks in Bowman's layer. Keratoconus is most commonly an isolated disorder, although several reports describe an association with Down syndrome, Leber's congenital amaurosis, and mitral valve prolapse. The differential diagnosis of keratoconus includes keratoglobus, pellucid marginal degeneration and Terrien's marginal degeneration. Contact lenses are the most common treatment modality. When contact lenses fail, corneal transplant is the best and most successful surgical option. Despite intensive clinical and laboratory investigation, the etiology of keratoconus remains unclear. Clinical studies provide strong indications of a major role for genes in its etiology. Videokeratography is playing an increasing role in defining the genetics of keratoconus, since early forms of the disease can be more accurately detected and potentially quantified in a reproducible manner. Laboratory studies suggest a role for degradative enzymes and proteinase inhibitors and a possible role for the interleukin-1 system in its pathogenesis, but these roles need to be more clearly defined. Genes suggested by these studies, as well as collagen genes and their regulatory products, could potentially be used as candidate genes to study patients with familial keratoconus. Such studies may provide the clues needed to enable us to better understand the underlying mechanisms that cause the corneal thinning in this disorder.

Histology and transmission electron microscopy of the cornea in xeroderma pigmentosum type C

Xeroderma pigmentosum is a very rare precancerous skin disease that is triggered by sunlight. It is caused by a defect in the DNA repair system and causes benign and malignant transformations. Only eye tissues that come into contact with UV light are affected, such as the lids, conjunctiva and cornea. We describe a patient who suffered from xeroderma pigmentosum type C, showing the typical skin alterations but no sign of malignancy. A perforating keratoplasty was performed on both eyes because of the dense opacity of the corneas. The corneal buttons obtained were examined by light and transmission electron microscopy. Degeneration was found only in the basal-cell layer of the corneal epithelium. The most severe morphological changes were seen in Bowman's layer, the subepithelial stroma, Descemet's membrane and the corneal epithelium. Bowman's layer was often interrupted or replaced by a degenerative pannus, which extended into the underlaying stroma. Subepithelial "channels" were localized in the basal epithelium and protruded into the subepithelial stroma. In both corneas, Descemet's membrane contained different amounts of so-called lattice collagen, and the remaining endothelial cells in the left cornea contained numerous melanin granules.