title: Corneal sensitivity in diabetic patients subjected to retinal laser photocoagulation.
abstract: OBJECTIVE
  To determine the changes in corneal sensitivity to different stimulus modalities in diabetes mellitus (DM)1 and DM2 patients with retinopathy, and to explore whether argon laser photocoagulation exacerbates sensitivity loss in diabetic patients.
  
  
  METHODS
  Corneal sensitivity to different modalities of stimulus was determined in one randomized eye in 52 patients with DM1 (n = 35) or DM2 (n = 17), and in 27 healthy subjects. Medical history was obtained from all the patients, including age, sex, time from DM diagnosis, type of diabetes, time from onset of retinopathy, type of diabetic retinopathy, and type of argon laser treatment. Corneal sensitivity was determined using a gas esthesiometer. Mechanical, chemical, and thermal (heat and cold) stimuli were applied on the central cornea.
  
  
  RESULTS
  Sensitivity thresholds to selective mechanical, chemical, and cold stimulation were significantly higher in DM patients compared to controls. Sensitivity threshold to mechanical and chemical stimuli was higher in DM2 than in DM1 patients. In DM1 patients, mechanical threshold increased with time after DM diagnosis. No correlation was found between sensitivity thresholds to chemical or thermal stimulation and the age of the patient, type of retinopathy, or time from its diagnosis. Laser treatment generated a further impairment of corneal sensitivity.
  
  
  CONCLUSIONS
  Corneal sensitivity to mechanical, chemical, and thermal stimulation is decreased in DM patients, suggesting that diabetes affects homogeneously the different types of sensory neurons innervating the cornea. Corneal sensitivity appears to be more disturbed in DM2 than in DM1. Laser treatment of DM patients generates a further impairment in corneal sensitivity, probably as the result of physical damage to ciliary nerves.
authors: Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant, Spain.
authors: Waldir
authors: W
authors: Neira-Zalentein
authors: Juha M
authors: JM
authors: Holopainen
authors: Timo M T
authors: TM
authors: Tervo
authors: Fernando
authors: F
authors: Borrás
authors: M Carmen
authors: MC
authors: Acosta
authors: Carlos
authors: C
authors: Belmonte
authors: Juana
authors: J
authors: Gallar
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D057908:Argon Plasma Coagulation / Q000379:methods; D003080:Cold Temperature; D003315:Cornea / Q000503:physiopathology*; D003922:Diabetes Mellitus, Type 1 / Q000150:complications; D003924:Diabetes Mellitus, Type 2 / Q000150:complications; D003930:Diabetic Retinopathy / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D006358:Hot Temperature; D006801:Humans; D017075:Laser Coagulation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010812:Physical Stimulation; D011183:Postoperative Complications / Q000175:diagnosis* / Q000503:physiopathology; D012160:Retina / Q000601:surgery; D012684:Sensory Thresholds / Q000502:physiology*; D013268:Stimulation, Chemical; D055815:Young Adult