In Vivo Confocal Microscopy and Anterior Segment Optic Coherence Tomography Findings in Ocular Ochronosis.

Elif Demirkilinc Biler,Suzan Guven Yilmaz,Melis Palamar,Pedram Hamrah,Afsun Sahin

doi:10.1155/2015/592847

Abstract

Purpose. To report clinical and in vivo confocal microscopy (IVCM) findings of two patients with ocular ochronosis secondary due to alkaptonuria. Materials and Methods. Complete ophthalmologic examinations, including IVCM (HRT II/Rostock Cornea Module, Heidelberg, Germany), anterior segment optical coherence tomography (AS-OCT) (Topcon 3D spectral-domain OCT 2000, Topcon Medical Systems, Paramus, NJ, USA), corneal topography (Pentacam, OCULUS Optikgeräte GmbH, Wetzlar, Germany), and anterior segment photography, were performed. Results. Biomicroscopic examination showed bilateral darkly pigmented lesions of the nasal and temporal conjunctiva and episclera in both patients. In vivo confocal microscopy of the lesions revealed prominent degenerative changes, including vacuoles and fragmentation of collagen fibers in the affected conjunctival lamina propria and episclera. Hyperreflective pigment granules in different shapes were demonstrated in the substantia propria beneath the basement membrane. AS-OCT of Case 1 demonstrated hyporeflective areas. Fundus examination was within normal limits in both patients, except tilted optic discs with peripapillary atrophy in one of the patients. Corneal topography, thickness, and macular OCT were normal bilaterally in both cases. Conclusion. The degenerative and anatomic changes due to ochronotic pigment deposition in alkaptonuria can be demonstrated in detail with IVCM and AS-OCT. Confocal microscopic analysis in ocular ochronosis may serve as a useful adjunct in diagnosis and monitoring of the disease progression.

Highlights

Alkaptonuria (AKU) is a disorder of phenylalanine/tyrosine metabolism due to a defect in the enzyme homogentisate 1,2-dioxygenase (HGD)
Excess homogentisic acid (HGA) is deposited as an ochre-colored pigment in collagen-rich tissues, such as bone, cartilage, and skin, causing a bluish-black discoloration, termed “ochronosis.” In “ocular ochronosis,” which is very rare, ochronotic pigmentation can be found in the sclera, conjunctiva, and limbic cornea as reported in single-case presentations [2,3,4]
In a previously reported case, it has been shown that ochronotic pigmentation of the eye may cause progressive peripheral corneal thinning and results in the induction of astigmatism in the axis of the lesion [6]

Summary

Introduction

Alkaptonuria (AKU) is a disorder of phenylalanine/tyrosine metabolism due to a defect in the enzyme homogentisate 1,2-dioxygenase (HGD). This recessive disease is caused by mutations in the HGD gene, leading to a build-up of homogentisic acid (HGA), a tyrosine degradation product, which can cause degenerative arthritis and calcific aortic stenosis [1]. Excess HGA is deposited as an ochre-colored pigment in collagen-rich tissues, such as bone, cartilage, and skin, causing a bluish-black discoloration, termed “ochronosis.” In “ocular ochronosis,” which is very rare, ochronotic pigmentation can be found in the sclera, conjunctiva, and limbic cornea as reported in single-case presentations [2,3,4]. Laser IVCM is a growing technique for the study of the cornea and conjunctiva at the cellular level and has been widely used to evaluate both their physiological and pathological states in the living eye [7,8,9,10]

Objectives

Methods

Conclusion