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Digital archive of theses discussed at the University of Pisa


Thesis etd-04012017-161441

Thesis type
Tesi di dottorato di ricerca
Thesis title
Ophthalmological evaluation in severely obese patients undergoing bariatric surgery: a pilot, monocentric, prospective, open-label study.
Academic discipline
Course of study
tutor Prof. Nardi, Marco
  • gastric by-pass surgery
  • obesity
  • ophthalmic examination
Graduation session start date
Background: There are known ophthalmologic alterations described in severely obese patients regarding the optic nerve head, the lens and the fovea. The aim of this study is to examine various ophthalmologic parameters in severely obese patients before and after gastric bypass surgery and to evaluate if there is a difference of the parameters studied related to the extent and timing of weight loss .
Methods: Fifty-seven patients with a mean body mass index value of 43.5 Kg 3.5 Kg/m2 and a mean age of 46.2 years were prospective evaluated. All patients underwent a complete ophthalmological evaluation before, 3 months and one year after bariatric surgery. Visual acuity, intraocular pressure, central corneal thickness measurement, indirect fundus ophthalmoscopy with 90D Volk’s lens and optical coherence tomography of the fovea and of the optic nerve head were performed in all patients enrolled. Anthropometric parameters were also registered at baseline, 3 months and one year after gastric bypass surgery.
Results: all the ophthalmologic parameters evaluated were within normal range at baseline and after gastric bypass surgery. At baseline blood pressure value were directly and significantly related with intraocular pressure values (p<0.05, R 0.35). Blood pressure,
particularly systolic values, was significantly and inversely related with retinal nerve fiber layer thickness, particularly in the temporal sector (RE p<0.05 r-0.31; LE p<0.01 r -0.43). Moreover, minimum foveal thickness values were significantly and inversely related with body mass index (RE p<0.02 r-0.40; LE p<0.02 r -0.30) at baseline. Thirty-two patients underwent gastric bypass surgery and for all of them we have available data both at 3 months and after one year. A significant reduction of blood pressure and body mass index has been observed (p<0.05) both after three months and after one year (p<0,05). Moreover, regarding ophthalmologic parameters, the RNFL thickness increased significantly in our population in both eyes in the superior sector (p<0,005), and in the left eye also in the inferior and temporal sector (p<0,05).
Conclusions: At baseline although all the ophthalmologic parameters were within normal limits, the inverse correlation between blood pressure and retinal nerve fiber layer thickness could explain the major susceptibility of obese patients to develop glaucomatous optic nerve head damage; and similarly the inverse correlation between body mass index and minimum foveal thickness value may explain a major susceptibility to develop maculopathy. After gastric bypass surgery, blood pressure values and body mass index significantly ameliorated and regarding ophthalmologic parameters there was a significant increase of retinal nerve fiber layer thickness in both eyes. So, the weight reduction and the consequent reduction of blood pressure value seems to influence positively ophthalmologic parameters.
Certainly, additional data are needed to confirm our first impressions