Corneal thickness in trachomatous dry eye.

PURPOSE: To investigate the effect of severe desiccation on corneal thickness in scarring trachoma by comparing the thickness of normal and trachomatous dry eye corneas. METHODS: Ultrasonic pachymetry was used to measure the corneal thickness at nine points in the central and peripheral cornea (superior, superonasal, nasal, inferonasal, inferior, inferotemporal, temporal, superotemporal) in 45 eyes of 27 patients with trachomatous dry eye and 54 eyes of 31 normal subjects. RESULTS: The average thickness of the nine sites in the central and midperipheral cornea was significantly less in trachomatous dry eyes than normal eyes. The superior cornea was the thickest area in both groups, measuring 574.03+/-31.62 microm in trachomatous dry eyes and 611.33+/-34.99 microm in normal eyes (p<0.001). The centre of the cornea was the thinnest, measuring 510.43+/-32.12 microm in trachomatous dry eyes and 546.27+/-36.20 microm in normal eyes (p<0.001). CONCLUSIONS: The thickness of the central and midperipheral cornea was significantly reduced in patients with trachomatous dry eye. The chronic state of severe desiccation, tear film instability and increased immune activation in trachomatous dry eye may contribute to this thinning.

Malondialdehyde and antioxidant enzyme levels in the aqueous humor of rabbits in endotoxin-induced uveitis.

PURPOSE: To investigate the role of oxidative stress in endotoxin-induced uveitis. METHODS: Lipopolysaccharide was injected intravitreally into the right eyes of rabbits. Sterile saline was injected intravitreally into the left eyes as a control. Inflammation was assessed according to clinical score, aqueous humor cell count, and protein levels. Malondialdehyde, superoxide dismutase, glutathione peroxidase, catalase, and nitrite levels were measured in the aqueous humor. RESULTS: The clinical grade (p < 0.01), inflammatory cell count (p < 0.001), and protein content (p < 0.001) were significantly higher in the aqueous humor of eyes with uveitis than in that of controls. Malondialdehyde (p < 0.01) and nitrite (p < 0.001) levels in the aqueous humor of eyes with uveitis were significantly higher than in the control group. Superoxide dismutase (p < 0.001), glutathione peroxidase (p < 0.001), and catalase (p < 0.001) levels were significantly lower in the aqueous humor of eyes with uveitis than in that of the controls. CONCLUSIONS: Oxygen free radicals may be implicated as a mediator of inflammation in endotoxin-induced uveitis. The increase in free radicals in the aqueous humor may play a role in the pathogenesis of endotoxin-induced uveitis.

Increase of free oxygen radicals in aqueous humour induced by selective Nd:YAG laser trabeculoplasty in the rabbit.

PURPOSE: To investigate the impact of selective Nd:YAG laser trabeculoplasty on free oxygen radicals and antioxidant enzymes of the aqueous humour in the rabbit. METHODS: One eye of 18 rabbits was subjected to 360 degrees selective laser trabeculoplasty (LT) with a frequency-doubled Nd:YAG laser (532 nm). The anterior chamber aqueous humour was aspirated 3, 12 hours and 1, 3, 7, 10 days after treatment. Lipid peroxide (LPO) and glutathione S transferase (GST) levels and superoxide dismutase (SOD) activities of aqueous humour were measured. RESULTS: Concentrations of LPO in the aqueous humour of the treated eyes were significantly higher than the untreated eyes until the 7th day. Aqueous SOD activity significantly decreased 3 hours after LT and remained low until day 7. Aqueous GST levels were significantly decreased between 12 hours and 7 days after the LT. CONCLUSIONS: Selective LT was followed by an immediate increase in the aqueous humour LPO concentration and decreases of SOD and GST in the rabbit, probably due to photovaporization and photodisruption caused by the frequency-doubled Nd:YAG laser. The increased aqueous LPO levels suggest that free oxygen radicals are formed in the pigmented trabecular meshwork during LT, and may be responsible for the inflammatory complications of this procedure.

Microbiologic analysis of aqueous humor in phacoemulsification.

PURPOSE: This study was designed as a microbiologic survey of the fluids aspirated from the anterior chamber at the end of cataract extraction performed by phacoemulsification, and to correlate the contamination rate of the anterior chamber to the surgical technique used. METHODS: One hundred and one consecutive patients (126 eyes) who underwent cataract extraction by phacoemulsification and posterior chamber intraocular lens implantation were included in the study. Microscopical examination, culture, and determination of the number of colonies were carried out on the bacteria and fungi in the anterior chamber fluids aspirated at the end of surgery, before final suture placement. RESULTS: Anterior chamber fluids yielded positive cultures in nine specimens (8.14%), six of which were identified as coagulase-negative staphylococci. Quantification disclosed colony counts ranging between 2-10 and 10-40 per mL. CONCLUSIONS: Preliminary results in a small population show that the contamination of the aqueous humor is significantly less frequent if the cataract extraction is performed by phacoemulsification.

Three-day course of oral azithromycin vs topical oxytetracycline/polymyxin in treatment of active endemic trachoma.

PURPOSE: The aim of this study on endemic trachoma was to carry out a comparison of azithromycin (3-day course, oral dose of 10 mg/kg per day) with conventional treatment (topical oxytetracycline/polymyxin ointment; twice a day for 2 months) in a rural area near Sanliurfa, Turkey. METHODS: Ninety-six subjects with active trachoma were randomly assigned conventional or azithromycin treatment. Subjects were examined 1, 2, 3, and 6 months after the start of treatment. Clinical findings were recorded for each eye. Swabs were taken from upper eyelids 3 and 6 months after the start of treatment for direct fluorescein antibody test. RESULTS: By six-month follow-up, trachoma had resolved clinically in 43 (89.58%) of the 48 subjects who received azithromycin, compared with 33 (68. 75%) of the 48 who were treated conventionally. Microbiological success rates (direct fluorescein antibody test negativity) were 83. 33% in the azithromycin group and 62.50% in the conventional therapy group. Compliance with both treatments was good. By 6 months, 14.58% of the subjects in azithromycin group and 33.33% of the subjects in the topical treatment group were reinfected. There were significant differences in the efficacy of the treatment effects and the re-emergence of disease between the two treatment groups. Azithromycin was well-tolerated. CONCLUSIONS: These results indicate that azithromycin may be an effective alternative for patients with active trachoma. As a systemic treatment, a 3-day course oral dose has important potential for trachoma control.

Ketorolac-tobramycin combination vs fluorometholone-tobramycin combination in reducing inflammation following phacoemulsification cataract extraction with scleral tunnel incision.

OBJECTIVE: The objective of this study was to compare the efficacy of ketorolac-tobramycin combination with fluorometholone-tobramycin combination in the control of ocular inflammation after endocapsular phacoemulsification cataract surgery with scleral tunnel incision. PATIENTS AND METHODS: This was a prospective, randomized, investigator masked, 2-week, single-center study. Ocular examinations were carried out preoperatively and postoperatively on days 1 (baseline), 2, 3, 7, and 14. There were 60 patients (30 in each treatment group) undergoing uncomplicated cataract-lens implant surgery enrolled and randomized in the study. The baseline parameters were similar in the two study groups. At each visit comprehensive ocular examinations were performed and a 4-point (0 to 3) grading system was used to record findings of the burning/stinging sensation, blurred vision, ocular discomfort, conjunctival hyperemia, anterior chamber flare, and anterior chamber cells. RESULTS: There was no statistically significant difference between the treatment groups in the findings of the ocular inflammation at any of the postoperative visits. Both treatments were equally well tolerated. CONCLUSIONS: This study suggests that ketorolac may be an alternative to some corticosteroids (fluorometholone). It is generally accepted that fluorometholone is not as potent an anti-inflammatory as prednisolone the most commonly used steroid following cataract extraction.

Endothelin-1 increase in aqueous humour caused by frequency-doubled Nd:YAG laser trabeculoplasty in rabbits.

PURPOSE: To study the effect of Nd:YAG laser trabeculoplasty (LT) on endothelin-1 (ET-1) concentration of aqueous humour and intraocular pressure (IOP) in rabbits. METHODS: One eye of each of 18 pigmented rabbits was subjected to 360 degrees LT with a frequency-doubled Nd:YAG laser (532 nm), and IOP was measured with a Tono-Pen tonometer before treatment. Post-LT IOP measurements followed by aqueous humour aspiration were performed under general anaesthesia at 3 and 12 h and 1, 3 and 7 days after the treatment. The concentration of ET-1 in aqueous humour was measured by means of a radioimmunoassay. RESULTS: In the eyes that had undergone LT, the concentrations of ET-1 in the aqueous humour were significantly increased at 3, 12 and 24 h after the treatment compared with the contralateral eyes. ET-1 concentrations at 3 and 7 days after LT, however, did not differ significantly from the corresponding contralateral control values. IOP increased following the treatment at 3 and 12 h. IOP values were significantly lower in the treated eyes at 1, 3 and 7 days after the treatment than in the control eyes. CONCLUSIONS: The results show that LT in rabbits was followed by an immediate and short-term increase in aqueous humour ET-1 that might be caused by leakage from uveal tissue. This may be responsible for the release of prostaglandins causing the IOP increase and inflammatory complications of LT.

Effects of frequency-doubled Nd:YAG laser trabeculoplasty on diurnal intraocular pressure variations in primary open-angle glaucoma.

In order to investigate the effects of laser trabeculoplasty (LT) on diurnal intraocular pressure (IOP) variations in 36 eyes of 30 cases with primary open-angle glaucoma (POAG) in which medical treatment was terminated, the IOP curves, recorded 24 h before as well as 24 h and 12 weeks after LT were compared. Twelve weeks after LT, significant IOP decreases were observed: 36.42% in the mean IOP, 29. 77% in the mean peak IOP and 50.04% in the mean pressure range. LT might therefore have beneficial effects on the diurnal IOP variations in cases with POAG.

Experimental intravitreal application of trovafloxacin in rabbits.

This study was performed to examine the retinal toxicity of trovafloxacin, a broad-spectrum fourth-generation fluoroquinolone, in rabbit eyes after intravitreal injection. The left eyes of 20 albino rabbits were divided into four groups, and each was injected intravitreally with 0.1 ml of trovafloxacin in a 50-microg, 100-microg, 250-microg or 500-microg concentration. The right eyes of these rabbits served as control and received normal saline solution. Retinal function was assessed from the electroretinogram (ERG), and retinal structure was also examined by ophthalmoscopy and histologic study (light microscopy). The intravitreal injections of 50 microg, 100 microg, and 250 microg trovafloxacin did not significantly change the ERG a-wave, b-wave or the oscillatory potential throughout the follow-up period of 4 weeks. While no ERG changes were observed at 4 weeks after injection, in the 3 eyes that received trovaloxacin 500 microg/0.1 ml, the a-wave amplitudes showed a diminution of 56-49% and those of b-waves one of 53-44% of the preinjection amplitudes at 4 weeks after injection, but oscillatory potentials remained unchanged in the other 2 rabbits intravitreally injected with 500 microg trovafloxacin. However, in none of the injected eyes and the control eyes in all groups were ophthalmoscopically visible fundus changes and histologic abnormality observed. The results suggest that intravitreally injected trovafloxacin at a dose of up to 500 microg is nontoxic to the rabbit retina. If future studies in other species confirm our findings, intravitreal trovafloxacin may be a good alternative in the treatment and prevention of clinical bacterial endophthalmitis.

The role of oxidative stress in diabetic retinopathy.

PURPOSE: To investigate the role of oxidative stress in the development of diabetic retinopathy. METHODS: This study included 25 patients with diabetic retinopathy (group I), 34 patients with non-insulin-dependent diabetes mellitus without any angiopathy complications (group II) and 26 healthy subjects (group III). The serum malondialdehyde (MDA)-like metabolite levels as an index of lipid peroxidation, the erythrocyte glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and serum vitamin C levels of the patients and healthy subjects were measured. RESULTS: The mean serum concentration of MDA-like metabolites of patients in group I was 4.38 +/- 1.31 nmol/ml, in group II was 3.38 +/- 0.95 nmol/ml and in group III was 2.61 +/- 0.85 nmol/ml. There were significant differences between the groups (p = 0.001 for group I compared with group II, p = 0.0001 for group I compared with group III and p = 0.002 for group II compared with group III). There was a significant correlation between the serum lipid peroxidation concentrations and duration of the disease (r = 0.36, p = 0.047). The mean erythrocyte GSH-Px and SOD levels of group I were respectively 68.97 +/- 18.04 and 1597.78 +/- 296.46 U/g Hb, of group II were 64.30 +/- 19.26 and 1581.33 +/- 278.08 U/g Hb, and of group III were 65.52 +/- 17.58 and 1587.44 +/- 281.17 U/g Hb. There were no significant differences among the antioxidant enzyme levels in the three groups (p > 0.05). The mean serum vitamin C level in group I was 42.72 +/- 8.90 mumol/l, in group II was 49.26 +/- 11.52 mumol/l and in group III was 58.57 +/- 9.75 mumol/l. There were significant differences among the mean serum vitamin C levels of the three groups (p = 0.02 for group I versus group II p = 0.001 for group I versus group III and p = 0.002 for group II versus group III). CONCLUSIONS: Free radicals forming in diabetes mellitus and increasing over time may play a role in the development of diabetic retinopathy, which is an important complication of the disease.

A survey of trachoma: the histopathology and the mechanism of progressive cicatrization of eyelid tissues.

The aim of this study is to demonstrate the spectrum of conditions encompassed by the term 'trachomatous cicatrization of eyelid tissue', to discuss the mechanisms of scar tissue formation and to describe sequelae in this potentially blinding condition. Specimens of eyelid tissues were taken from 27 upper eyelids of 21 patients with entropion who underwent surgical procedures and 2 post-mortem upper eyelids with severe trachomatous entropion. Upper palpebral conjunctival swabs and biopsy specimens were taken from 5 patients with active trachoma and they were examined by fluorescence microscopy and routine histopathological methods. Conjunctival impression cytology samples were collected in all patients. In specimens taken from patients with active trachoma the inflammatory infiltrate was organized as lymphoid follicles in the underlying stroma and impression cytology showed cytoplasmic elementary bodies. In specimens taken from patients with scarring trachoma light microscopy studies showed subepithelial fibrous membrane formation, squamous metaplasia and loss of goblet cells, pseudogland formation in conjunctiva, degeneration of orbicularis oculi muscle fibres, subepithelial vascular dilatation, localized perivascular amyloidosis and subepithelial lymphocytic infiltration. Accessory lachrymal glands and the ducts of glands were compromised by subepithelial infiltration and scarring. The contraction of the subepithelial fibrous tissue formed by collagen fibres and anterior surface drying are the main factors contributing to the chronic cicatrization and entropion formation.

The treatment of severe trachomatous dry eye with canalicular silicone plugs.

PURPOSE: To evaluate the effects of temporary canalicular occlusion with silicone plugs on trachomatous dry eye patients who were on maximal tolerable medical therapy. METHODS: Forty-four trachomatous dry eye patients who had Schirmer testing with topical anaesthetic measuring 5 mm or less and a tear film break-up time of 5 s or less were included. After the lacrimal efficiency test with dissolvable collagen punctal plugs, silicone canalicular plugs were placed in 22 trachomatous dry eye patients. The other 22 patients in the untreated control group were allowed to continue their medical therapy. Pretreatment and post-treatment evaluations included subjective patient assessment, rose Bengal and fluorescein staining, tear film break-up time, Schirmer testing, conjunctival impression cytology and goblet cell counting. RESULTS: Six months after plug placement, 18 eyes (82%) of 22 patients had subjective improvement and all these patients successfully wore plugs for at least 6 months. There were statistically significant differences between the pretreatment and post-treatment test results including rose Bengal and fluorescein staining scores, tear film break-up times and Schirmer testing measurements. Impression cytology showed improvement of squamous metaplasia in 17 eyes (77%). Eight of the patients (36%) were able to decrease dependency on topical therapy. Ten of the patients (45%) completely stopped using artificial tears. There were statistically significant differences between the two groups in the total symptom scores, staining scores, tear film break-up time, Schirmer testing, impression cytology scores and goblet cell counts. CONCLUSION: In cases where topical tear supplementation is insufficient to relieve the signs and symptoms of severe dry eye and the lacrimal puncta have not already been closed by the trachomatous cicatrising process, occlusion of the canaliculi may be useful to prevent drainage of both natural and artificial tears. Canalicular occlusion improves the objective signs and subjective symptoms and may significantly decrease dependency on tear supplements in selected patients.