Cytological factors relating to posterior capsule opacification following cataract surgery.

This paper discusses tissue culture experiments with human lens epithelial cells that demonstrate that cells from all parts of the anterior capsule have regenerative capacity, that the cells from younger patients proliferate more than those from older patients and that cells from cataractous lens retain their growth potential. Epithelial cells may be removed from the anterior capsule by EDTA in an infusion fluid and epithelial cells adhere more to PMMA than HEMA intraocular lenses. The clinical implications of these studies are discussed.

The fixed dilated pupil after cataract surgery--is it related to intraocular use of hypromellose?

Hypromellose can be used as a viscoelastic substance during cataract surgery. Two groups of patients, one group operated on using hypromellose, the other using sodium hyaluronate as a viscoelastic substance were followed up 2-6 months postoperatively. A total of 16.7% of the eyes operated on using hypromellose developed a non-reactive semidilated pupil whereas none of the eyes from the control group developed this phenomenon. It was concluded that there is a probable link between the intraocular use of hypromellose and abnormal pupils after cataract surgery.

Lens epithelial cells adhere less to HEMA than to PMMA intraocular lenses.

Following cataract surgery proliferation of residual lens epithelial cells may occur causing secondary opacification and loss of visual acuity. Using an in vitro system the abilities of bovine and porcine lens epithelial cells to adhere to two types of intraocular lens have been assessed. Lens epithelial cells adhere significantly less to lenses composed of poly 2 hydroxyethylmethacrylate (HEMA) than to polymethylmethacrylate (PMMA).

The human anterior lens capsule--an attempted chemical debridement of epithelial cells by ethylenediaminetetracetic acid (EDTA) and trypsin.

The addition of edetic acid (EDTA) or trypsin to the infusion during a simulated extracapsular cataract extraction on cadaver eyes facilitates the removal of lens epithelial cells from the anterior capsule. Modification of the chemical composition of infusions used during extracapsular surgery may maximise lens epithelial cell removal and hence reduce the incidence of opacification of the posterior capsule after cataract extraction.

Human retinal extract stimulates the proliferation of human lens epithelial cells.

The proliferation of lens epithelial cells remaining attached to the capsule after extracapsular cataract extraction represents a potential cause of posterior capsule opacification. In view of the reported mitogenic effects of eye derived growth factors on lens epithelial cells in animal studies, we determined to establish whether the human retina produces a factor capable of inducing a similar response in human lens epithelial (HLE) cells. We report that an extract of the human neural retina is capable of increasing the proliferative capacity of HLE cells in culture by 50%. The possible mechanisms are discussed. The presence of such a growth factor in the human eye would have important consequences for the epithelial cells remaining after cataract surgery.

Cytological factors relating to posterior capsule opacification following cataract surgery.

Simulated extracapsular cataract extractions on cadaver eyes were performed which demonstrated that the cells of the anterior capsule remain largely intact and that only a small amount of cortical lens matter remains postoperatively. Human lens epithelial cells from normal and cataractous lenses were grown in culture. There was no appreciable difference in growth rate between cells from normal and those from cataractous lenses or between equatorial and central capsule cells. The cells grew from the cut edges of the capsule, suggesting that release from contact inhibition is an important factor in stimulating proliferation. The daughter cells became increasingly abnormal and metaplastic in successive generations, but there was no evidence of differentiation into fibroblasts within the 35-day culture period, suggesting that a retinal growth factor may be involved with the fibrosis occurring in opacification of the posterior capsule. A small anterior capsulotomy will release fewer cells from contact inhibition and hence reduce cell proliferation after extracapsular cataract extraction.

Ophthalmic findings in a group of ambulatory patients infected by human immunodeficiency virus (HIV): a prospective study.

Twenty-eight patients with either the acquired immune deficiency syndrome (AIDS) or persistent generalised lymphadenopathy (PGL) were studied prospectively as outpatients for up to one year. Six patients had fundal cotton wool spots at some stage of their follow-up and all six suffered opportunistic infections associated with AIDS. We suggest that ocular abnormalities may be prognostic for opportunistic infection in AIDS and discuss the wide range of ophthalmic complications consequent to HIV infection.

Low vision aids--evaluation in a general eye department.

A review was undertaken of all patients referred for Low Vision Aid (LVA) assessment in the Wandsworth Health Authority over eighteen months. The majority of referrals (72 per cent) could have near visual acuity improved and were prescribed an LVA. Of those prescribed only 23 per cent found the LVA useful at home. Fifty-three per cent of patients preferred a high reading addition or hand magnifier to the prescribed LVA. The most helpful indications to predict success in using an LVA were found to be age of the patient, the type of eye disease and the strength of magnification required.

The ophthalmological features of AIDS and AIDS related disorders.

The ocular findings in 38 patients infected by the Human T Cell Lymphotropic Virus Type III (HTLV III) are reviewed. Twenty patients were suffering from the Acquired Immunodeficiency Syndrome (AIDS) and 18 from the HTLV III related disease Persistent Generalised Lymphadenopathy (PGL). Cotton wool spots were found in the retinae of 8 patients at some stage of their disease and the prognostic significance of these is discussed. Cytomegalovirus (CMV) Retinitis was an ocular complication in eight of the patients with AIDS. The therapeutic effects of a new anti-viral drug, di-hydroxy propoxymethyl guanine (DHPG), are discussed.