Laser-assisted cataract surgery and other emerging technologies for cataract removal.

As we near the end of this century, refractive cataract surgery has become a reality through concerted contributions from ultrasonic phacoemulsification, foldable intraocular lens (IOL) implantation technology and keratorefractive surgery. As we enter the new millennium, our sights are set on realizing another dream: accommodative IOL surgery. Towards achieving this goal, many advances have been made in both techniques and technology of cataract removal. Lasers in particular have been under investigation for cataract removal for nearly two decades. The technology has now reached a stage where cataract can indeed be removed entirely with laser alone. Neodymium:YAG and erbium:YAG are the laser sources currently utilized by manufacturers of laser phaco systems. Initial clinical experience reported in the literature has served to highlight the capabilities of lasers and the need for further refinement. Despite the excitement associated with the availability of this alluring new technology for cataract removal, it is necessary to develop more effective laser systems and innovative surgical techniques that optimize its capabilities if laser phaco surgery is to be a genuine improvement over current techniques.

Physical and mechanical principles of phacoemulsification and their clinical relevance.

A clear understanding of the physical and mechanical principles that govern phacoemulsification can facilitate usage of this technique for effective and efficient cataract removal in a variety of clinical situations. This article addresses separately, concepts pertaining to the three essential components of phacoemulsification, namely, irrigation, aspiration and emulsification. Machine settings are suggested for the various techniques presently in use. Finally, alternative approaches for lens removal that are currently being investigated are briefly discussed.

Conjunctival transplantation for corneal surface reconstruction--case reports and review of literature.

Corneal persistent epithelial defects (PED) can occur due to various causes. In diffuse ocular surface disease, they often occur secondary to depletion of limbal stem cells. A number of complications occur secondary to PED and successful treatment usually requires conjunctival surgeries for corneal surface reconstruction. We report two cases of chemical injury successfully treated by two such procedures. This report highlights the encouraging results of limbal transplantation and reviews the literature in the management of PED with limbal stem cell loss.

Principles and paradigms of pediatric cataract management.

Propensity for increased postoperative inflammation and capsular opacification, a refractive state that is constantly in a state of flux due to growth of the eye, difficulty in documenting anatomic and refractive changes due to poor compliance, and a tendency to develop amblyopia, makes management of cataract in the child different from that in the adult. The recent past has unraveled several caveats of pediatric cataract management-the importance of atraumatic surgery and complete removal of lens matter, benefits of in-the-bag intraocular lens (IOL) implantation, role of titrating IOL power to counter refractive changes due to growth of the eye, prudery of continuously following these eyes for early detection of aphakic glaucoma and benefits of some surgical innovations. Although these promise to significantly improve our management of pediatric cataract, their long-term benefits are yet to be determined. We will also have to harness newer techniques, especially in the areas of wound construction and capsule management, and will have to develop effective strategies for the refractive management of infantile aphakia.

Oxidative damage to the eye lens caused by cigarette smoke and fuel smoke condensates.

Cigarette smoking is reported to increase the risk of cataract. Likewise, the use of smoky cooking fuel is implicated in the etiology of cataract. In an effort to understand the cellular and molecular basis, the in vitro and in vivo cataractogenetic effects of these smoke condensates have been studied using isolated rat lenses and pigmented rats. Isolated capsulated rat lenses are incubated with cigarette smoke condensate (CSC) and firewood smoke condensate (FSC) for varying periods, with and without antioxidants, in the presence and absence of light. CSC and FSC permeate the lens capsule, impart colour and opacify the lens in a light- and dose-dependent manner. Antioxidants offer partial inhibition against the above damage. The condensates contain polycyclic aromatics which generate reactive oxygen species such as O2 photodynamically, and ppb levels of Fenton metal ions which induce oxidative reactions through .OH. Smoke induced damage possibly occurs through systemic absorption and transport of toxic components to several tissues, and specially into the lens, wherein the turnover is slow, leading to chronic accumulation causing oxidative damage to the constituent molecules and to consequent lenticular opacity.