Ophthalmological conditions in kittens and young cats

Kittens and young cats are frequently presented at veterinary clinics with “eye problems”. In this article Thomas Large and Ben Blacklock give an overview of some of the most common — and not-so-common — conditions that may be encountered.

Introduction

A wide variety of ophthalmological conditions can present in kittens and young cats in practice. This article aims to review both common and uncommon clinical presentations of congenital and acquired ocular diseases to provide guidance on diagnosis and treatment. The conditions have been subdivided into those affecting different anatomical locations (Table 1) but inevitably crossover can exist, with some conditions affecting multiple ocular structures.
 

Globe

Microphthalmia

Microphthalmia is the congenital failure of the globe to fully develop and can present as a unilateral or bilateral reduction in globe size, with signs such as enophthalmos, third eyelid protrusion and entropion ( 1 ) ( 2 ). Some case reports have shown that microphthalmia may present alongside other congenital ocular abnormalities such as eyelid coloboma, corneal dermoids, choroidal coloboma and choroidal hypoplasia ( 1 ) ( 2 ). If secondary disease of the cornea or discomfort is caused by concurrent abnormalities then enucleation of the affected eye(s) may be necessary ( 2 ).

Periocular tissues

Eyelid coloboma

Eyelid colobomas are a congenital maldevelopment of the eyelids, for which the underlying cause is currently unknown. The condition can be unilateral or bilateral and usually involves the upper temporal eyelid margins, with the severity of defects varying in size from small notches to a complete absence of larger sections of eyelid tissue ( 3 ). Eyelid colobomas are often reported to be associated with other ocular abnormalities of the anterior and posterior segments — such as persistent pupillary membranes, retinal dysplasia and absence of a tapetum — as part of a “colobomatous syndrome” ( 1 ). In practice, the clinical signs relating to eyelid colobomas can vary depending on the severity of the defect. Clinical signs commonly include corneal inflammation, corneal ulceration and corneal irritation secondary to corneal exposure (due to ineffective closure of the eyelids) and trichiasis from adjacent hair shafts misdirected onto the cornea ( 1 ) ( 3 ). An example of an eyelid coloboma is shown in Figure 1. 
 

The treatment options for eyelid colobomas are predominantly surgical and focus on restoring as much of a functioning palpebral fissure as possible, as well as preventing trichiasis and further corneal irritation. For mild defects with inversion of the eyelid, a standard Hotz-Celsus procedure may be sufficient to prevent further corneal irritation from trichiasis. For larger defects several different surgical techniques are available which involve the transposition of adjacent periocular tissue to reconstruct the eyelid margin. One example, the Roberts and Bistner procedure, involves surgically dissecting a myocutaneous pedicle and transposing this from the lateral lower lid up to the lateral upper lid defect to create a new eyelid margin ( 4 ). [...]