Diabete Mellito e Lenti a Contatto. Diabetes Mellitus and Contact Lenses

This work on Diabetes Mellitus and Contact Lenses had two main purposes: the first was to review a moderate part of the literature about this field of interest, preceded by a short review on cornea and its alterations as Diabetes Mellitus occurs. The second target was to conduct a small survey among Italian diabetics and healthy subjects who wore contact lenses. The aim of the survey was to find if the results would have agreed with the previous review. The analysis based on the survey, conducted by giving the same questionnaires to healthy and diabetic subjects, was not prospective as all the interviewed were already wearing contact lenses or had worn them before. In particular, the survey was based on some parts of Efron’s survey, made among diabetic patients and practitioners in the UK in 1997. In addition to this, the results of the survey were compared with other considerations, which emerged during the review. The aim of the questionnaire was to find out if RGP contacts were used in higher percentage among diabetics rather than in healthy subjects, and to see if diabetics had higher rate of drop out or interruptions in contact lenses’ use due to discomfort or dry eye. The method used for the retrospective survey consisted in proposing 39 anonymous questionnaires, of which 20 were proposed to healthy contact lenses’ users and 19 to diabetics; of them only 9 wore contacts. Finding diabetic contact lenses’ users was pointed out as the main struggle for the success of the survey. The questionnaires were analysed with the percentage on the amounts of answers. The results showed that 45% of diabetics used RGP CLs against the 10% of the healthy subjects, meaning that RGP were preferred for diabetic corneas, even if the reasons of this choice were not asked. For what concerns interruption of contacts lenses, none of the healthy subjects interrupted CLs because of dry eye, the 10% of them interrupted because of discomfort, while among people affected by Diabetes Mellitus 11% dropped because of dry eye and another 11% dropped because of discomfort. These results are in agreement with literature, even if there are some limitations that can compromise the accuracy of the data: firstly, the samples consisted in a small amount of people, increasing the errors’ rate due to comprehension of the questions and accuracy in the answers. Another limitation was the subjective nature of the data, as no objective measurements were collected during the survey. Moreover, the samples came from two Italian regions (Veneto and Friuli Venezia Giulia), which means that the survey is not representative of the Italian population. In conclusion, further analysis would be necessary to confirm the results of this survey. The main considerations achieved by reviewing literature were that Diabetes Mellitus not only afflicts the retina (causing Diabetic Retinopathy) but also the corneal tissue. Indeed, it causes abnormalities in all corneal layers giving fragility, slower times of recovery from both epithelial and endothelial oedema, disfunctions in Na+/K+-ATPase’s pump and faster aging. Furthermore, the storage of glucose and sorbitol during hyperglycaemia and chronic hyperglycaemia can lead to alterations on the tissue’s transparency causing blurred vision and to refractive changes, which can sway from hyperopia to myopia very easily. Finally, diabetic eyelids are more prone to infections. If these infections become chronic then contact lenses are not to recommend to the person affected by Diabetes Mellitus. The alterations listed above summarize why Diabetes Mellitus is a relevant but relative contra-indication to contact lenses’ use: the practitioner should take in consideration the clinical picture of the diabetic cornea and decide if whether or not prescribe contact lenses, especially if the subject hardly follows the prescriptions given by the specialist.