Evaluation of different treatment modalities on the efficacy of hydroxypropyl Guar (HP-Guar) formulation on tear film stability (TFS) in subjects exposed to adverse environmental conditions

Abstract The study aimed to assess the efficacy of hydroxypropyl guar (HP) formulation (Systane) to protect tear film parameters under desiccating environment using protection and relief treatment modalities. The subjects were exposed to adverse environmental conditions using a Controlled Environment Chamber (CEC) where the relative humidity (RH) was 5% and the ambient temperature was 21 °C and screened for Tear break-up time (TBUT), Tear film evaporation rate (TFER) and lipid layer thickness (LLT) using the HIRCAL grid, Servomed EP3 Evaporimeter and Keeler’s TearScope-Plus respectively. Significant improvement in LLT was noticed in the protection modality. The mean tear film evaporation rate doubled after exposure to the humidity of 5% to a value of 105.37 g/m2/h (0.29 µl/min). All subjects displayed a significant reduction in non-invasive tear break-up time (NITBUT) with a mean NITBUT of 7.7 s after exposure to a desiccating environment for 15 min. A significant increase in NITBUT after the instillation of the drops was recorded in both methods. The results obtained from this study showed that a solution containing HP-Guar significantly improves tear film parameters under a desiccating environment. Apart from the tear evaporation rate, all tear parameters showed improvement after the use of HP-Guar eye drops. It is evident that tear film parameters respond differently to the management modalities and using CEC has the potential to provide researchers with a readily available method to evaluate the efficiency of tear supplementation

Efficacy of hydroxypropyl-guar drops in improving tear film index and ocular surface dynamics using two treatment methods under a controlled desiccating environment

Aim: This study aimed to assess the efficacy of hp-guar eye drops on tear film index and ocular surface dynamics under desiccating conditions using protection and relief treatment modalities.Methodology: The 12 normal, non-dry eye participants were subjected to adverse environmental conditions using a Controlled Environment Chamber (CEC) where the relative humidity (RH) was 5% and the ambient temperature was 21 °C. The participants were screened for ocular symptoms, tear osmolarity, ocular surface temperature (OST), tear production using the Ocular Surface Disease Index questionnaire (OSDI), OcuSense TearLab Osmometer, FLIR System ThermaCAM P620, and Schirmer strips. Tear production was calculated by the Tear Function Index test (TFI).Results: The mean tear film osmolarity decreased significantly from 296 mOsm/L at 40% RH to 285 mOsm/L at 5% RH (p = 0.01). Conflicting responses were seen for osmolarity in protection and relief. Mean tear osmolarity was significantly higher in the protection method in comparison to the relief method (p = 0.005). The mean TFI increased from 557 at 40% to 854 at 5% (p = 0.02). A significant increase in TFI was observed in the relief method in comparison with both 40% (p = 0.001) and 5% (p = 0.04). In the relief method, the mean TFI score went up to 1139 when hp-guar was installed. A significant improvement in ocular comfort was experienced in both the protection (p = 0.041) and relief (p = 0.010) methods at 5% RH. The instillation of hp-guar drops in the relief method resulted in a significant reduction in OST. The mean OST dropped to 33.01 ºC, significantly lower than the recorded OST for both normal (p = 0.040) and dry (p = 0.014) environmental conditions. Conclusion: Hp-guar drops significantly improve tear film parameters under a desiccating environment, however, tear film parameters respond differently to the management modalities. In the protection method, tear film osmolarity was protected against a dry environment, while in the relief mode, an improvement in tear production and a decrease in ocular surface temperature were seen. Hp-guar performance could be maximized for the management of exposure to adverse environments by using a treatment protocol that targets the most affected parameters in each group of patients. Using CEC has the potential to provide researchers with a readily available method to evaluate the efficiency of tear supplementation.</p

Accommodative Response in Patients with Central Field Loss: A Matched Case-Control Study

Purpose: This study was conducted to evaluate the accommodative response in young participants with visual impairment in comparison with visually normal participants. Methods: Fifteen participants with confirmed visual impairment and 30 visually normal participants aged 12–15 years were recruited. Accommodative response was measured using autorefractor (Grand Seiko WV500) at distances of accommodative demand of 33, 25, and 20 cm. The targets were one-line-above participant threshold acuity. The participants’ accommodative responses were compared between both groups after calibration for refractive errors and the vertex distance of the glasses. Visual acuity and refractive status were also assessed. Results: The age was not significantly different between both participant groups. The visual acuity of visually impaired patients was 6/30 to 6/240, and that of visually normal participants was 6/7.5 or better. Ten of the visually impaired patients and 29 of visually normal participants were myopic. In total, 61–73% of visually impaired patients showed an accommodative lead. Five subtypes of accommodative response were observed. In general, the accommodative inaccuracy increased with increasing accommodative demand. However, the visually normal participants largely exhibited an accommodative lag. A mild-to-moderate relationship was observed between visual acuity and accommodative response (r = 0.3–0.5, p &lt; 0.05). Conclusion: Accommodative response in young visually impaired patients can be variable and on an individual basis. Low vision specialists should anticipate accommodative response outside the normal range. Therefore, we shall consider evaluating each patient’s accommodative response before prescribing any near addition lenses. Accommodation inaccuracy is often more complex than predicted due to increased depth of focus caused by reduced visual acuity

Analysis of basal and reflex human tear osmolarity in normal subjects: assessment of tear osmolarity

Purpose: The aim of this study is to evaluate the difference between reflex and basal tear osmolarity among healthy normal subjects. Method: The right eyes of 20 healthy normal male subjects aged 20 to 40 years were recruited for this study. The inclusion criteria for the subjects were the Ocular Surface Disease Index questionnaire score of less than 12 and wetting length of the phenol red thread of more than 10 mm. Tear film osmolarity was assessed using TearLab osmometer. Basic tear osmolarity was measured normally without inducing any irritation to the eye. In order to stimulate reflex tear, subjects were asked to open their eye as long as they can till they feel ocular surface irritation (minimum 20 s). Results: The mean score on the Ocular Surface Disease Index questionnaire was 5.5 ± 3. The mean value obtained from the phenol red thread was 21 ± 4.5 mm. There were no statistically significant differences between the osmolarity readings of basal and reflex tear osmolarity ( p > 0.05). The mean value was 308 ± 12 and 306 ± 9 mOsm/l for basic and reflex tear osmolarity, respectively. Conclusion: This study found that the osmolarity of the basal and reflex tears fell within the same range. The values found in this study are in agreement with published results for normal subjects