Objective: To evaluate the ultrasonic attenuation and amount of soluble proteins of human diabetic lens.
Materials and methods: The examination was performed in the Clinic of Eye Diseases of Kaunas University of Medicine. The study included 4 groups of patients (110 eyes). The first group consisted of healthy subjects (32 eyes), the second group--of patients with initial senile cataract (13 eyes), the third group--patients with type I diabetes mellitus (24 eyes) and the fourth group--patients with type II diabetes mellitus (41 eyes). In vivo examination of human lenses was carried out by Mentor A/B ultrasonic imaging system using 7 MHz A-mode probe and the ultrasound attenuation coefficient was calculated. The phacoemulsification technique has been used for cataract extraction. Gel chromatography of the supernatant fraction on the Sepharose CL 6B column was used for fractionation of soluble lens proteins. Protein concentration was determined by the method of Lowry using bovine serum as standard.
Results: The least mean lens thickness of 3.58+/-0.18 mm was found in the healthy patients' group. There was a significant difference (p<0.05) between the thicknesses of the lenses in the healthy group and in the type I diabetic group. The difference between senile cataract and type II diabetic cataract was insignificant (p>0.05). The mean ultrasound attenuation coefficient in the groups of healthy and type I diabetic cataract was nearly the same, as so as in the groups of senile cataract and type II diabetic cataract. The significant difference (p<0.001) in the values of attenuation coefficient was found between the groups of type I and type II diabetics. The amount of soluble proteins was lowest in cataractous lenses of patients with type II diabetes (0.053+/-0.007 mg/1 mg tissue) and highest in the lenses of patients with type I diabetes (0.063+/-0.004 mg / 1 mg tissue), but those differences were statistically insignificant. Distribution of soluble proteins into the different molecular mass fractions in the group of type I diabetic lenses was found to be similar to the type II diabetic lenses and to the patients with senile cataract.
Conclusions: The diabetic changes stronger influence the thickness of lenses of young people; in the elder age the difference between the thickness of senile and diabetic cataract is not so distinct. Ultrasound attenuation coefficient has a tendency to be higher in patients with senile and type II diabetic cataract. Human lens crystallins of patients with type I diabetes and type II diabetes are damaged at the same degree, the amount of soluble proteins decrease with age and biochemical changes of the lens.