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Abstract

As previously reported in the literature, hyperbaric oxygen delivery seems to modify the natural course of retinitis pigmentosa. In order to evaluate these first encouraging data, 48 affected subjects were separately studied in two subgroups (cases and controls). All patients underwent yearly an ophthalmological examination completed by a maximum amplitude electroretinogram, conducted according to our 'differential derivation' system, a new recording technique specifically designed to enhance the signal-to-noise ratio. Oxygen delivery was provided regularly for 90 min daily (2.2 Absolute Atmosphere) in three cycles according to a standard protocol. In the cases, electroretinographic mean values were as follows: at T0 (basal) 4.68 +/- 3.81 microV; after one year (T1) 8.46 +/- 5.71 microV; at two years (T2) 10.7 +/- 7.6 microV; at the end of the study (T3) 14.4 +/- 11.7 microV. In the controls, electroretinographic mean values were as follows: at T0 4.92 +/- 3.05 microV; at T1 5.04 +/- 3.07 microV; at T2 3.46 +/- 2.77 microV: at T3 2.97 +/- 3.61 microV. Amplitudes showed a remarkable (p<0.001) increase in the cases, while a slightly significant (p<0.02) decrease was evident at the end of the study in the controls. In our opinion, retinal oxygen availability may be critical in retinal degeneration and hyperbaric oxygen delivery, inducing hyperoxia, seems to be able to bring about the rescue of the retinal photoreceptors helping them in their metabolic requirements. Unfortunately, our study demonstrates an increase in electroretinographic responses only, which may not necessarily also mean an evident change in visual acuity.

Systematic Review of Randomized Clinical Trials on Safety and Efficacy of Pharmacological and Nonpharmacological Treatments for Retinitis Pigmentosa

“…Demographic characteristics are summarized in Table 2 . The 19 studies included in this systematic review evaluated the following interventions in RP patients: two on HBO [ 5 , 6 ], one on topical brimonidine tartrate [ 14 ], five on vitamins supplementation [ 8 , 26 – 28 , 33 ], 4 on DHA supplementation [ 29 – 31 , 34 ], 2 trials on lutein [ 9 , 10 ], one on gangliosides' supplementation [ 32 ], one on nilvadipine [ 13 ], one on beta-carotene [ 11 ], one on CNTF [ 15 ], and one on oral valproic acid [ 12 ]. Results of the RCTs included in this review are summarized in Table 3 .…”

“…While in some trials randomization appeared to have been executed properly, that is, an unpredictable sequence of treatment allocation was concealed adequately from people recruiting participants into the trial, the following biases have arisen in the trials included in this review ( Figure 2 ): Sequence generation was not specified or performed in seven studies [ 5 , 6 , 13 – 15 , 28 , 33 ]. Allocation concealment was not specified or performed in five trials [ 5 , 6 , 13 , 28 , 33 ]. Five studies were unmasked [ 5 , 6 , 12 , 13 , 33 ].…”

“… Allocation concealment was not specified or performed in five trials [ 5 , 6 , 13 , 28 , 33 ]. Five studies were unmasked [ 5 , 6 , 12 , 13 , 33 ]. …”

“…Nine trials were excluded because they did not match one or more inclusion criteria and one was excluded because it was not eligible [ 16 – 25 ]. All the remaining 19 RCTs were included in the systematic review [ 5 , 6 , 8 – 11 , 13 – 15 , 17 , 26 – 34 ] ( Figure 1 ).…”

“…Nonpharmacological interventions are based on strategies of light protection as evidences indicate that some genetic types of pigmentary retinopathies are partly light-dependent [ 4 ]. Hyperbaric oxygen therapy has been also proposed for RP patients in order to promote photoreceptors survival [ 5 , 6 ].…”