Influence of laser irradiation on endogenous hyaluronan in rabbit iris and aqueous humor.

PURPOSE: To monitor changes of endogenous hyaluronan in the iris tissue and aqueous humor after an isolated trauma to the iris by argon laser irradiation of the anterior surface of the iris. METHODS: Iris and aqueous hyaluronan concentrations in rabbit were measured with a radiometric assay at different time points after laser irradiation. RESULTS: Total hyaluronan content in iris tissue increased 3-fold to a peak concentration of 71-72 microg/g at 1 and 2 days after laser treatment. Aqueous hyaluronan increased to a maximum of about 1.6 microg/ml at 2 h and 12 h after laser irradiation of the iris. CONCLUSIONS: The iris tissue responds with increased hyluronan synthesis to an isolated iris argon laser irradiation and it seems to be the most important source of aqueous hyaluronan.

Synthesis of hyaluronan by normal and wounded rabbit iris.

BACKGROUND: Endogenous hyaluronan has been found in different tissues in the normal and traumatized eye. However, the main source, the biological aspects and the full potential role of hyloronan are still unclear. METHODS: Hyaluronan production was studied both in organ culture and in vivo, using a double-label protocol with [35S]sulfate and [3H]glucosamine. RESULTS: [3H]glucosamine and [35S]sulfate were incorporated into hyaluronan and sulfated glycosaminoglycans in normal and in traumatized iris tissue in organ culture and in vivo. There was low relative hyaluronan synthesis in vivo, only 2% of total incorporated [3H]glucosamine in normal irides. Increased relative incorporation of [3H]glucosamine into hyaluronan was seen after operative trauma to iris tissue both in vivo and in vitro. CONCLUSION: Our findings demonstrate synthesis of hyaluronan by normal and traumatized iris. The iris seems to be the most important source of aqueous hyaluronan.

Endogenous hyaluronan in the normal and traumatized rabbit iris.

PURPOSE: Hyaluronan concentration in the iris tissue after iridectomy was studied in order to establish the influence of trauma on the production of hyaluronan in the anterior chamber of the eye and whether the iris participates in this process or not. METHOD: Hyaluronan was measured with a radiometric assay at different time points after surgery and identified with specific histochemical staining. RESULTS AND CONCLUSIONS: The concentration of hyaluronan in iris tissue peaked two days after surgery, reaching an average of 115.3 (S.E.M.:+/-12.2) microg/g. It then decreased slowly to almost normal values after 3 to 5 weeks. Histochemistry demonstrated the most intense hyaluronan staining in the iris stroma and in iridial processes around the iridectomy two days after the operation. Our findings indicate in situ synthesis of hyaluronan in the iris tissue.

Extracellular glutathione peroxidase and ascorbic acid in aqueous humor and serum of patients operated on for cataract.

Patients operated on for cataract (32 men/75 women, aged 50-93 years) were studied with respect to antioxidative agents in aqueous humor and serum. Extracellular glutathione peroxidase (eGSHPx) was demonstrated in aqueous humor for the first time by a radioimmunoassay, the concentration of eGSHPx being 0.66(0.18) mg/l (mean(S.D.)). The concentration of eGSHPx in serum was 3.81(0.84) mg/l, and its level in aqueous humor was 18(7)% of that level. Serum selenium had positive correlations with both serum eGSHPx (r = 0.34, P < 0.001) and aqueous humor eGSHPx (r = 0.25, P = 0.011). However, there was no relation between the concentrations of eGSHPx in aqueous humor and in serum, suggesting that the maintenance of eGSHPx levels in the two fluids is controlled by different mechanisms beside selenium status. There was an inverse correlation between age and serum eGSHPx but not with aqueous humor eGSHPx. The concentration of ascorbic acid in aqueous humor was 2.04(0.58) mmol/l, and it was closely correlated to the level of ascorbic acid in serum (0.052(0.032) mmol/l), r = 0.58 (P < 0.001). The ratio between the level of ascorbic acid in aqueous humor and that in serum was 39(17). There was no significant difference among patients with nuclear (n = 39), cortical (n = 20), posterior-subcapsular (n = 23) or mixed (n = 23) lens opacity with respect to levels of eGSHPx and ascorbic acid in serum and aqueous humor. Since serum ascorbic acid is related to ascorbic acid intake, its association to aqueous humor ascorbic acid indicates that dietary habits are important for maintaining that level which could play an important role in protecting ocular tissue against oxidative damage. The role of eGSHPx secreted into aqueous humor in the oxidant defence system needs further study.

The results of penetrating keratoplasty for keratoconus.

At the Department of Ophthalmology, University Hospital in Lund, Sweden, keratoconus is the most common indication for penetrating keratoplasty. We studied 77 keratoplasties performed on keratoconic eyes between 1989-1991. Postoperative corrected visual acuity was better than or equal to 0.5 in 65 eyes (84.4%), and 30 eyes (39%) had visual acuity of 1.0. The mean postoperative astigmatism was 3.75 D with a range of 0-12.5 D. Eight patients underwent relaxing incision with satisfactory results in 6 patients. Graft rejection was observed in 6 eyes (7.8%). The most serious complication seen in our group of patients was a retrocorneal fibrous membrane that developed in one patient.

Visual results after RK.

The series of radial keratotomy (RK) in 79 myope eyes in 60 patients was studied to evaluate improvement of uncorrected visual acuity. The main aim with radial keratotomy was to help patients see better without glasses or contact lenses. Myopia ranged from -1.0 D to -9.0 D. Forty-two eyes (53%) achieved uncorrected visual acuity (VA) of 1.0 or better and 73 eyes (92%) better than 0.5. The follow-up period ranged from 3 months to 3.5 years. Postoperatively the most common complication was undercorrection. The risk for progressive myopia made surgeons cautious not to overcorrect patients and to leave them slightly myopic.