Targeted nutrition for optimising vitreous health in subjects with symptomatic vitreous degeneration

Purpose: Degeneration of the vitreous, the homogenous gel that fills the posterior segment of the eye, is ubiquitous during life and leads to the entoptic phenomenon, vitreous floaters. Floaters impact negatively on the quality of life and visual function of its sufferers. Unfortunately, most floater sufferers are not treated since the available treatment options, pars plana vitrectomy and laser vitreolysis, are not readily proffered to these patients due to their accompanying potential, sight-threatening complications. It follows from the foregoing that a low-risk yet effective therapy is warranted for the management of symptomatic vitreous degeneration. This PhD thesis reports three main studies (Chapters 3 – 5) which were conducted to: (a) investigate the impact of vitreous degeneration on photopic and mesopic contrast thresholds (Study 1); (b) assess the use of a novel objective methodology for quantifying vitreous opacities as a measure of treatment success in patients who underwent laser vitreolysis for managing symptomatic vitreous floaters (Study 2); and (c) investigate the impact of targeted nutrition with a micronutrient formulation on vitreous health in patients with symptomatic vitreous degeneration (Study 3). Methods: Study 1 was a case-control study that enrolled an age-matched sample of 115 subjects, comprising 30 subjects with vitreous floaters (cases) and 85 healthy subjects (controls). Best corrected visual acuity (BCVA), flicker thresholds, photopic and mesopic functional contrast thresholds (at 10 cycles per degree) were measured for all participants. Further, the cases were split into cases with (n=12) and without (n=18) posterior vitreous detachment (PVD), and their contrast thresholds were compared with the controls, to determine the effect of PVD on contrast. Study 2 was a retrospective study of 77 patients who underwent Nd:YAG laser vitreolysis and had a minimum follow-up of 3 months. Quantitative vitreous opacity areas, the lack of need to proceed to vitrectomy, patient satisfaction outcomes post vitreolysis, BCVA and intraocular pressure (IOP) were assessed at baseline and all follow-ups. In Study 3, 61 patients with vitreous floaters were randomised to consume daily, the active supplement consisting of 125 mg L-lysine, 40 mg vitamin C, 26.3 mg Vitis vinifera extract, 5 mg zinc, and 100 mg Citrus aurantium or placebo for 6 months. Subjective change in visual discomfort from floaters, BCVA, letter contrast sensitivity, photopic functional contrast sensitivity with positive and negative contrast polarity, and quantitative vitreous opacity areas were assessed for all participants at baseline and final visits. Results: In study 1, photopic and mesopic contrast thresholds were lower by 37.4% and 27.5%, respectively, when the cases were compared with the controls (p=0.028 and p<0.001 for photopic and mesopic contrast thresholds, respectively). Further, photopic and mesopic contrast were lower by 64.0% and 30.3% in cases with PVD compared with controls (p=0.001 and p=0.014 for photopic and mesopic contrast, respectively). In study 2, there was a significant decrease in vitreous opacity areas (objective treatment success of 89.6%) at the final visit following laser vitreolysis (p<0.001). In addition, subjective treatment success reported at 1-month and the last follow-up were 77% and 71%, respectively. There was a lack of need of vitrectomy in 65 eyes. Intra-operative complications recorded included posterior lens injury in one eye and retinal bleed in another eye. For study 3, the active group reported a significant decrease in their visual discomfort from floaters (p<0.001), whereas the placebo group had no significant change in their visual discomfort (p=0.416) after supplementation. At 6 months, there was a significant decrease in vitreous opacity areas in the active group (p<0.001) and an insignificant increase in vitreous opacity areas in the placebo group (p=0.081). Also, there was a significant improvement in photopic functional contrast sensitivity in the active group after supplementation (p=0.047). Conclusions: Study 1 demonstrates that subjects with vitreous degeneration have diminished photopic and mesopic contrast thresholds compared with controls. This finding highlights the negative impact of vitreous degeneration on the quality of vision. Study 2 reveals that Nd:YAG laser vitreolysis results in both objective and symptomatic improvement in at least two-thirds of patients who undergo the procedure. Vitreous opacity areas quantification can be employed by clinicians as an objective outcome measure for diagnosing, planning and quantifying the treatment outcomes for vitreous floater patients. The findings of Study 3 indicate improvements in vision-related quality of life and visual function of patients suffering from vitreous floaters after supplementation with the active formulation. Notably, these improvements were confirmed by the decrease in vitreous opacity areas in the active group. This targeted dietary intervention should be considered to support patients with symptomatic vitreous degeneration.