[In vivo confocal microscopy observation and evaluation of sensation in diabetic corneas].

OBJECTIVE: To test the changes of corneal sensation in diabetic patients and to observe the diabetic corneas using confocal microscopy. METHODS: One hundred and thirty-two diabetic patients were enrolled in this study. The diabetic history and medication were recorded. The FBG and HbA(1c) were checked for every patient. The patient's eye was systemically checked, including the IOP, visual acuity, cornea sensation, lenses, and the fundus. Two hundred patients of other diseases were enrolled as controls. The cornea of 85 patients and 56 controls were checked by the confocal microscopy. The right eyes of both patients and controls were used for analysis. RESULTS: The cornea sensation of diabetic patients was significantly depressed as compared to that of the controls (P < 0.01). The depression of cornea sensation was related to the course of the disease, the presence of diabetic retinopathy and the degree of the diabetic retinopathy (P < 0.05). The confocal microscopy revealed that there was a higher corneal epithelium edema rate (11.76%) in diabetic patients than that of the controls (1.79%) (P < 0.05). The nerve fiber density of the diabetic patients was decreased and there were some morphological changes in the nerve fiber of diabetic patients, such as sparse, slim, less branches, less long fibers, edema and zigzag of the fibers. CONCLUSION: The depression of the corneal sensation in diabetic patients is probably caused by the reduction and the degeneration of the corneal nerve fibers.

[Analysis of the effectiveness of laser in situ keratomileusis two years after surgery].

OBJECTIVE: To evaluate the effectiveness of laser in situ keratomileusis (LASIK) for myopia after 2 year follow-up. METHODS: LASIK surgery was performed for 95 eyes (49 cases) with refractive dioptres (from -1.00 to -16.50 D), and then followed up for more than 2 years. The preoperative spherical equivalent was -1.00(-)-16.50 (-6.73 +/- 2.02) D. Patients were divided into two groups including group I with mild to moderate myopia (< or = -6.00 D) and Group II with severe myopia (more than -6.00 D). RESULTS: In group I, uncorrected visual acuity more than and equivalent to 1.0 was in 40 eyes (93.02%), more than and equivalent to 0.8 in 43 eyes (100%). In group II, uncorrected visual acuity larger than and same as 1.0 was in 37 eyes (71.15%), larger than and same as 0.8 in 45 eyes (86.54%), larger than and same as 0.5 in 50 eyes (96.15%), and less than 0.5 in 2 eyes (3.85%). The mean spherical equivalent changed from (-4.14 +/- 0.86) D to (-0.04 +/- 0.14) D in group I and from (-9.00 +/- 1.64) D to (-0.08 +/- 0.20) D in group II. Significant difference was seen in these two groups (P < 0.001). The keratometric powers (K) were reduced from (44.31 +/- 0.78) to (40.11 +/- 1.23) and from (45.46 +/- 1.00) to (38.01 +/- 1.73) respectively, which showed significant difference (P < 0.001). CONCLUSION: The effectiveness of LASIK for mild to moderate myopia or severe myopia is promising and safe.

[Tear film function of patients with type 2 diabetes].

OBJECTIVE: To study the tear film function of patients with type 2 diabetes and to investigate the risk factors of dry eye in these patients. METHODS: Totally 111 patients with type 2 diabetes and 100 age- and sex-matched control subjects were studied. Tear film function was evaluated by dry eye syndrome, tear breaking up time (BUT), corneal fluorescein staining, Schirmer I test (SIt), and tear film lipid layer observation with tear scope. Dye eye score was calculated with the results of these tests. RESULTS: When compared with the controls, patients with type 2 diabetes showed higher dry eye score (diabetics 3.28 +/- 1.56, control 2.31 +/- 1.50, P < 0.01) and faster BUT [diabetics (6.50 +/- 4.84) s, control (12.26 +/- 7.16) s, P < 0.01], but similar SIt [diabetics (10.61 +/- 6.86) s, control (10.92 +/- 7.05) s, P > 0.05]. More diabetic patients were diagnosed as dry eye(diabetics 19.8%, control 8.0%, P < 0.05). According to their retinopathy, the diabetic patients were divided into three groups: without diabetic retinopathy (DR), with background DR, and with proliferative DR. For these three groups, the dry eye scores were 2.95 +/- 1.50, 3.38 +/- 1.48 and 4.11 +/- 1.60, respectively (P < 0.01); the SIt were (10.95 +/- 6.89) mm, (11.71 +/- 7.30) mm and (7.63 +/- 5.20) mm, respectively (P > 0.05); the BUT were (7.53 +/- 5.23) s, (5.88 +/- 4.10) s and (4.47 +/- 4.17) s (P < 0.05). Patients with DR were then devided into two groups: with photocoagulation and without photocoagulation. For these two groups, the dry eye scores were 4.71 +/- 1.14 and 3.26 +/- 1.15, respectively (P < 0.01); the BUT were (2.93 +/- 2.06) s and (6.26 +/- 4.36) s, respectively (P < 0.01); the SIt were (7.21 +/- 6.51) mm and (11.33 +/- 6.73) mm, respectively (P < 0.05); the rates of corneal fluorescein staining were 50.0% and 17.9%, respectively (P < 0.05). Dry eye score had a good correlation with diabetic retinopathy and photocoagulation (P < 0.01), but was poorly correlaed with age, gender, insulin, duration of diabetes mellitus, and metabolic control (P > 0.05). CONCLUSIONS: Patients with type 2 diabetes tend to develop tear film dysfunction. The disorders of tear film quantity and quality seem relevant to the stage of diabetic retinopathy and photocoagulation.

[Static and dynamic contrast sensitivity of myopic eyes before and after laser in situ keratomileusis].

OBJECTIVE: To evaluate the static and dynamic contrast sensitivity changes in myopic patients before and after laser in situ keratomileusis (LASIK). METHODS: Seventy-three eyes in 37 patients with myopia (with or without astigmatism) who received LASIK were tested for static and dynamic contrast sensitivities using the METRO VISION MON ELEC I system at 0.7, 1.4, 2.7, 5.5, 11, and 22 cpd and cps prior to LASIK, and at one-, three-, and six-month intervals after LASIK. RESULTS: All eyes gained naked visual acuity of more than 0.5 after LASIK. The contrast sensitivity was depressed at all frequencies 1 month after LASIK, as compared to one week prior to LASIK. The depression at 2.7, 5.5, 11 (P < 0.01) and 22 cpd (P < 0.05) was statistically significant for static contrast sensitivity, and also at 5.5 (P < 0.01) and 11 cps (P < 0.05) for dynamic contrast sensitivity. Myopic eyes between 6.25 D and 14.0 D, and astigmatic eyes 2 DC and more, suffered more static and dynamic contrast sensitivity depression than the myopic eyes between 1.25 D and 6.00 D and astigmatic eyes less than 2 DC. Contrast sensitivities were improved and exceeded preoperative levels 3 months after LASIK, and improved even more 6 months after LASIK. All sequences were statistically significant for static contrast sensitivity (P < 0.01), while only 2.7, 5.5, and 11 cps were statistically significant for dynamic contrast sensitivity (P < 0.01). The astigmatic eyes 2 DC and more showed less improvement, even below the preoperative level at 1.4 cps of dynamic contrast sensitivity. CONCLUSIONS: While temporary depression of contrast sensitivity for myopic eyes after LASIK was seen, contrast sensitivity soon returned to exceed preoperative levels at 3 months after LASIK, while improving even more 6 months after LASIK.

[Effect of negative pressure suction on rabbit optic nerve and retina].

OBJECTIVE: To study the effect of acute intraocular pressure (IOP) elevation on the optic nerve and retina in laser in situ keratomileusis (LASIK). METHODS: Acute IOP was increased to 65 mm Hg for different period of time (30 s, 1 min and 3 min) by using scleral suction on rabbit eyes. The tissues of retina and optic nerve of immediately extirpated group (instant group), of 2 weeks later extirpated group (recovery group) both after the negative pressure suction and of normal rabbit eyes were examined with electron and light microscope. RESULTS: After the negative pressure suction for 30 s, 1 min, and 3 min respectively, the optic nerve and retinal cells changed lightly; some part of optic nerve and retinal cells changed; optic nerve fibers and retinal cells changed sharply. CONCLUSION: Ultrastructural changes of retina and optic nerve may be induced by acute IOP elevation in LASIK. The longer the time, the more apparent the changes.