Correlation between Corneal Sensitivity and Peripheral Neuropathy in Type 2 Diabetics Attending the Endocrinology Clinic of University of Port Harcourt Teaching Hospital (UPTH), Nigeria

Aim: To correlate the occurrence of corneal sensory loss with peripheral neuropathy in Type 2 diabetics.

Study Design: A hospital-based case control study.

Place and Duration: A study conducted on type 2 diabetics attending the endocrinology clinic of University of Port Harcourt Teaching Hospital (UPTH), Rivers State, Nigeria between October 28th 2013 and February 28th 2014.

Methodology: Participants were selected using consecutive allocation of type 2 diabetics as they presented to the Endocrinology Clinic of University of Port Harcourt Teaching Hospital. Diabetes-free controls were recruited simultaneously. Data of each participant was documented on standard proforma and subsequently had ocular examinations. Central corneal sensitivity was assessed using a Cochet-Bonnet Aesthesiometer, peripheral neuropathy was assessed using the Biothesiometer.

Results: A total of 120 diabetics and 120 age and sex-matched controls constituted the study population. Their mean age was 55.6 ±10.5 years with an age range of 30 to 82 years (diabetics: 56.6 ±10.9 years and healthy control: 54.5 ±10.1 years). Corneal sensitivity in the right eye of diabetics was: 52.4±6.7 mm and 55.5±4.9mm in controls while that in the left eye was 51.1±9.0 mm in diabetics and 54.0±5.2 mm in control. The mean value pressure applied to the central cornea in diabetics was 0.54±0.16 gm/mm2 and 0.47±0.09 gm/mm2 in controls. The average vibration perception threshold in diabetics was 21.3±7.4 and 16.6±3.8 in control. Corneal sensitivity in diabetics with symptoms of neuropathy was 51.8±6.7 and 56.3 ±5.8 in diabetics without symptoms (p-value 0.014). The corneal sensitivity in diabetics with peripheral neuropathy-biothesiometer readings > 25 mV- was 46.5± 7.2 and 54.2 ±5.4 in diabetics without peripheral neuropathy-biothesiometer readings of <25mV (p-value <0.001).

Conclusion: Corneal sensitivity was significantly lower in diabetics with peripheral neuropathy when compared to diabetics without peripheral neuropathy.