Dietary α-lipoic acid prevents UVB-induced corneal and conjunctival degeneration through multiple effects.

PURPOSE: This study investigated the effects of dietary α-lipoic acid (α-LA) against ultraviolet B (UVB)-induced corneal and conjunctival degeneration in a mouse model. METHODS: Female CBA mice were randomly divided into five study groups, including blank control, UVB without α-LA, and UVB with dietary α-LA at 1, 10, and 100 mg/kg body weight. Following UVB exposure, corneal surfaces were assessed along with immunohistochemistry for nuclear factor-κB (NF-κB), cyclooxygenase-2 (COX-2), malondialdehyde (MDA) accumulation, and P63⁺ basal cell distribution. Matrix metalloproteinase (MMP)-2 and MMP-9 activities were determined by gelatin zymography. ELISA assay was performed to confirm the findings of immunohistochemistry for NF-κB, COX-2, and MDA, along with the levels of TNF-α and IL-6. Tear production and goblet cell density were determined after tear strip assay and periodic acid Schiff staining, respectively. RESULTS: The results showed that UVB irradiation caused corneal surface damage, polymorphonuclear leukocyte infiltration, and loss of P63⁺ basal cells. Dietary α-LA ameliorated the UVB-induced corneal damage while simultaneously reducing MDA accumulation and maintaining P63⁺ basal cell survival. NF-κB-p65, COX-2, TNF-α, IL-6, and MMP-9 activity were all reduced by dietary α-LA. In addition, α-LA helped to reverse aqueous tear reduction, conjunctival squamous epithelium metaplasia, and goblet cell loss after UVB exposure. CONCLUSIONS: Dietary α-LA can prevent UVB-induced corneal damage and can be used as a prophylactic agent prior to excessive UVB exposure.

Sub-Tenon anaesthesia: reduction in subconjunctival haemorrhage with controlled bipolar conjunctival cautery.

PURPOSE: To evaluate the effect of controlled conjunctival cautery on the frequency and extent of subconjunctival haemorrhage (SCH) associated with sub-Tenon anaesthetic (STA) injection in patients with various clotting states. METHODS: One hundred forty-four patients suitable for cataract surgery with STA were prospectively divided into four groups: group A (n=36) were on warfarin (INR 1.8-4.2); group B (n=48) on aspirin (75 mg); group C (n=12) on clopidogrel (75 mg); and group D (n=48) on no anticoagulant or antiplatelet agents. All patients had no other known coagulopathy. Each group was randomly divided into two subgroups, one of which received localised bipolar cautery under microscope control to the STA conjunctival entry site before tissue dissection, whereas the other served as a control. chi(2) and Fisher's exact tests were used to analyse the data with the SPSS package (v11.0). RESULTS: Conjunctival cautery reduced the frequency of SCH from 67 to 6% in group A (P=0.0001); from 37.5 to 4% in group B (P=0.005); from 50 to 0% in group C (P=0.9); and from 17 to 0% in group D (P=0.55). This overall reduction in SCH was highly significant (P<0.0001), especially in groups A and B. No statistically significant reduction in the extent of SCH was found. CONCLUSIONS: Controlled localised bipolar conjunctival cautery before STA injection may significantly reduce the frequency of SCH, especially in patients on warfarin or aspirin.

The protective effect of alpha-lipoic acid against oxidative damage in rabbit conjunctiva and cornea exposed to ultraviolet radiation.

PURPOSE: The purpose of this study was to determine the protective effect of alpha-lipoic acid against oxidative damage in rabbit conjunctiva and cornea exposed to ultraviolet radiation. METHODS: 20 rabbits weighing 2,500- 3,000 g were used, and we divided them into 4 groups with 5 randomly selected rabbits. The rabbits were exposed to 2 J/cm(2)/h of ultraviolet A radiation (UVA) in the range of 320-405 nm for 12 h per day within 90 days. The control group did not undergo any procedure, the UVA group was only exposed to UVA radiation. The PUVA group was treated with 8-methoxypsoralen and UVA. The alpha-lipoic acid group was administered 8-methoxypsoralen + UVA + alpha-lipoic acid. At the end of 90 days, the rabbits were killed by decapitation, and the eyes were enucleated. Both eyes of each rabbit were used for biochemical evaluation. Conjunctival and corneal free malondialdehyde (MDA), glutathione peroxidase (GSH-PX) and superoxide dismutase (SOD) levels were compared among the groups. RESULTS: Conjunctival free MDA levels were lower in the alpha-lipoic acid group compared with the UVA and PUVA groups (p < 0.05, p < 0.001, respectively). Both conjunctival SOD levels (p < 0.05, p < 0.01, respectively) and conjunctival GSH-PX levels (p < 0.01, p < 0.001, respectively) were higher in the alpha-lipoic acid group compared with other groups. Corneal free MDA levels were lower in the alpha-lipoic acid group compared with the UVA and PUVA groups (p < 0.01, p < 0.001, respectively). Both corneal SOD levels (p < 0.01, p < 0.01, respectively) and corneal GSH-PX levels (p < 0.01, p < 0.01, respectively) were higher in the alpha-lipoic acid group compared with the other groups. CONCLUSION: alpha-Lipoic acid which is considered as potent antioxidant protects the eye from the damaging effect of ultraviolet exposure.

Ocular side effects of PUVA-treated patients refusing eye sun protection.

We have investigated short- and long-term ocular side effects of psoralen plus UVA (PUVA) therapy in 82 patients who refused to wear UVA blocking sunglasses after the treatments. They had received 321.7 +/- 328.8 J/cm2 of UVA in 148.8 +/- 113.9 exposures over 2-4 years. Results were compared with findings obtained in 749 patients who shielded their eyes. They received 402.6 +/- 302.2. J/cm2 of UVA in 167.8 +/- 136.9 treatments over 2-6 years. 20 patients refusing eye sun protection developed conjunctival hyperemia and 21 patients decreased lacrimation. Among patients who adequately protected the eyes, we observed 5 cases of conjunctival hyperemia and 1 case of decreased lacrimation. Lens opacities did not develop in any patient. Adequate eye sun-protection is thus needed to avoid acute toxicity of cornea and conjunctiva but lens opacities do not appear to be a side effect of long-term PUVA-therapy.