Undoubtedly, Veterinary Ophthalmology developed with a slower pace in India because of lack of skilled personnels, inadequate instruments required for ophthalmic surgery of small and large animals and less number of availability of clinical cases. Gradually, owing to more awareness by pet and livestock owners they in turn had greater expectations from Veterinary Surgeons for application of advanced diagnostic and surgical procedures to treat the diverse ophthalmic affections. This was perhaps a triggering impetus to learn the modern veterinary ophthalmology and I got inspired to learn and develop this speciality in Clinic of my college.

Cataract is a common cause of visual impairment and blindness in dogs and has a wide variety of aetiologies, as well as the disabling effect on the animal. Cataracts present important welfare considerations for the owner. Visual impairment in dogs may lead to increased nervousness, aggression and reluctance to exercise, all of which may adversely affect the owner-pet relationship (1). The only effective mean of treatment for cataract is surgical extraction of diseased lens (2). Although vision is one of the important faculties for any living individual, dogs have very well developed olfactory lobe and have great sense of smell. They can move about easily in limited area familiar to them even with impaired vision. Cataract surgery was therefore not a common procedure in animals for many years. Quite often however,

(A) Anatomy of Lens The lens is anoptically clear, avascular, biconvex structure of crystalline appearance with an anterior surfaceless curved than the posterior surface, placed between the iris and the vitreous. It is suspended by the suspensory ligament of the lens which is attached to the ciliary body and equator of the lens. The lens consists of a central nucleus surrounded by the lens fibres and anterior epithelium, encapsulated in an elastic lens capsule. The anterior surface of the lens is in contact with the posterior surface of the iris whereas posterior surface is in contact with the vitreous. As the adult lens does not have a blood supply, its metabolic needs are met by the aqueous humour. The lens is composed of 65% water, 35% protein with scant amounts of electrolytes. The proteins can besubdivided into soluble proteins,

The speed with which changes in the eye can take place is challenging. Ophthalmic problems do not lend themselves to casual examination or ‘trial and error’ therapy. Therefore, to perform safe cataract surgery with good quality outcome, uniform minimum standard of diagnostic and clinical practice needed to be in place. Although cataract can be diagnosed by routine gross examination ofthe affected dog even then it is mandatary to develop a routine ophthalmic examinations in a consistent and organized manner to make a confirmatory diagnosis and plan the surgical technique for a favourable prognosis. A sequential examination starting right from history up to electroretinography may be performed as under: History » Gross Examination » Menace response test » Obstacle course test » dazzle or photic blink reflex » Light induced pupillary reflexes (direct/ consensual) » Corneal reflex test »Schirmer’s tear test

All animals with cataract are not suitable candidates for surgery. Pre-surgical assessment of a candidate is essential to make a safe judgement for surgical procedure to perform lensectomy. Failure in canine cataract surgery can be associated with poor case selection. A thorough ocular and physical examination should be performed to rule out other ocular diseases prior to cataract surgery. The cataractous lenses in both eyes must be mature to cause functional loss of vision. (24). The following prerequisites should be fulfilled before cataract extraction is recommended (6): The affected eye should have a significant visual deficit. For the patient to regain vision, its retina must be healthy and functional. if the fundus cannot be examined thoroughly (because of the cataract), retinal function should be evaluated with electroretinography (ERG) to ensure that retinal degeneration is not present as the patient history, signalment, and the speed of pupil contraction

Good cataract outcome depends on pre-operative selection of patients, the skills and knowledge of the eye surgeon, the surgical technique, the surgical facilities and environment, the post-operative care and the optical correction provided. Preoperative Procedures Owners are advised to instill antibiotic eye drop such as Moxifloxacin @ two drops b.i.d. for 7 days and eye drop tropicamide @ two drops b.i.d. for 2 days before the cataract surgery for proper dilation of pupil. Non-steroidal anti-inflammatory eye drops such as Flubriprofenis started t.i.d on the day before surgery. Further, tropicamide (1%) used as mydriatic agent is instilled 30 minutes before operation at the rate of two drops every 5 minutes in the eye to be operated. 0.5% povidone iodine drops are instilled on cornea prior to surgery.

Intra-operative complications Although the phacoemulsification technique costs higher, it provides shorter surgical time and less complication than extracapsular lens extraction (49). The most important intraoperative complications are anterior capsular fibrosis, radial tear of anterior capsule, posterior capsular rupture, vitreous prolapse and post-operative complications like uveitis and corneal oedema (50). The production of ultrasound energy in phacoemulsification is associated with heat generation that can result in damage to ocular tissue, in particular the corneoscleral wound site. Thermal damage to the corneo-scleral wound site may result in difficulty with wound closure and consequent risk of wound leakage, as well as damage to the adjacent corneal stroma and endothelium, fistula formation, and the induction of high degrees of post-operative astigmatism. The loss of adequate flow of irrigation fluid around the phacoemulsification tip is the key factor in the development of phacoemulsification-induced thermal injury. 

1. Gould, D. (2002). Clinical assessment of cataract in dogs. In Practice, 24: 28-34. 2. Dziezyc, J. (1990). .Cataract Surgery. Current approaches. Veterinary Clinics of North America: Small Animal Practice 20 (3): 737-754. 3. Gelatt, K.N. and Gelatt, J.P., (2001). Surgical procedures of the lens and cataracts. In: Gelatt KN, Gelatt JP (eds.). Small Animal Ophthalmic Surgery: Practical Techniques for the Veterinarian, Butterworth-Heinemann, Oxford, UK: 286-334. 4. Kecova, H. S. and Necas, A. (2004). Phacoemulsification and intraocular lens Implantation: Recent Trends in Catract Surgery. ACTA VET. BRNO: 73 85-92. 5. Ofri, R. (2013). Lens. In: MAGGS, D.J.; NILLER, P.E.; OFRI, R. (Eds.). Slatter’s Fundamentals of Veterinary Ophthalmology. Gainesville: Elsevier .272- 290.