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Aim: To assess the short-term efficacy of hypotonic 0.18% sodium hyaluronate in patients with evaporative tear-sufficient dry eye due to lipid tear deficiency (LTD)., Methods: This was a randomised, double-blind, controlled, exploratory study. A total of 10 patients with dry eye due to LTD were treated as follows: one drop of hypotonic 0.18% sodium hyaluronate in one eye and one drop of isotonic 0.3% hydroxypropyl-methylcellulose (HPMC)/0.1% dextran in the other eye. Non-invasive tear film break-up time (NIBUT) evaluated by using a tear scope with grid pattern and subjective ocular symptoms of dry eye were assessed at 15, 30, 60 and 90 min after instillation., Results: Both sodium hyaluronate and HPMC/dextran caused a significant (p<0.05) improvement in NIBUT and symptoms. Mean (SD) NIBUT in the sodium hyaluronate group was 3.2 (1.0), 6.4 (2.8), 5.5 (1.9), 5.3 (1.3) and 3.9 (1.7) s at 0, 15, 30, 60 and 90 min, respectively, compared with 3.6 (1.9), 5.5 (3.2), 5.0 (1.5), 4.4 (2.2) and 3.5 (1.2) s in the HPMC/dextran group. However, increase in NIBUT was significantly (p<0.05) greater and longer in the sodium hyaluronate group than in the HPMC/dextran group., Conclusion: Treatment with sodium hyaluronate and HPMC/dextran eye drops is useful for treating patients with dry eye due to LTD. However, sodium hyaluronate caused a significantly (p<0.05) greater increase in NIBUT values than HPMC/dextran in such patients.

Aims: To study the long term toxic effects of intraocular benzalkonium chloride (BAC)., Methods: 19 patients exposed to intraocular BAC preserved viscoelastic during cataract surgery in February 1999 developed severe striate keratopathy immediately postoperatively. 16 patients, including two who underwent penetrating keratoplasty, were studied in the period April to June 2000. Ocular symptoms, visual acuity, biomicroscopy, intraocular pressure, dilated funduscopy, specular endothelial microscopy, and corneal pachymetry findings were recorded. The corneal and iris specimens of the two patients who underwent keratoplasty were studied by light, transmission, and scanning electron microscopy., Results: Six males and 10 females, aged 64-98 years, were studied 14-16 months postoperatively. All patients were symptomatic. 12 patients had best corrected visual acuity of 6/12 or better and four patients of between 6/18 and 6/60. Five patients had corneal epithelial oedema and 11 had Descemet's membrane folds. The central corneal thickness, 620 (SD 71) microm, in affected eyes was significantly higher (p<0.005, two tailed paired t test) than that of the contralateral eyes, 563 (SD 48) microm. The endothelial cell density was significantly lower (p<0.0001, two tailed paired t test) in affected eyes: 830 (SD 280) cells/mm2 v 2017 (SD 446) cells/mm2. The mean average cell area was significantly higher in the BAC treated eyes: 1317 (SD 385) microm2 v 521 (SD 132) microm2. There was no significant difference in the coefficient of variation of cell size between the two eyes (p=0.3, two tailed paired t test). Two corneal specimens displayed morphological features of bullous keratopathy and other non-specific abnormalities. Extracellular melanosomes were present in a portion of the iris of one case., Conclusion: BAC is toxic to the corneal endothelium when used intraocularly, leading to severe striate keratopathy. This cleared in most cases but left varying degrees of residual stromal thickening in all eyes. If penetrating keratoplasty is required the results are excellent.

Methylcellulose has been used since 1976 to prevent damage to the corneal endothelium during operations for implantation of intraocular lenses. Originally one drop of a 1% solution was placed on the artificial lens just before its insertion. Later the anterior chamber was completely filled with a 2% solution of methylcellulose before implantation. In this way it is possible to maintain a space between the cornea and iris even if vitreous pressure is present and to operate without risk to the corneal endothelium. This paper demonstrates the safety of the intraocular use of methylcellulose on the basis of over 400 operations. The substance is cheap, universally available, and can be easily prepared for intraocular use.