A study was undertaken to determine the effect of polyethylene and polystyrene used in the manufacture of plastic items on colour perception. Colour vision was assessed using the Ishihara plates, panel 015 test and the Farnsworth Munsell 100-Hue test. Two factories were chosen at random. One factory (referred here as factory A) used virgin resin in pellet form (polyethylene) in the manufacturing of plastic containers to store consumer edible oil. The other factory (referred as factory B) used polystyrene to make plastic bags. A total of 39 healthy employees from factory A (mean age 26.4 :t 8.2 years) and 40 healthy employees from factory B (mean age 26.8 :t 9.6 years) were recruited in this study. A control group of 27 normal healthy subjects (mean age 27.4 :t 4.3 years) who were employees of UKM with no occupational involvement with petroleum derivatives were also recruited in this study and they performed the same colour vision tests. All subjects passed the Ishihara plates test showing that none of the subjects (employees of factory A and B, and control subjects) had a congenital red-green defect. All control subjects passed all of the colour vision tests whilst some employees of factories A and B failed the 015 and FM100 Hue tests. For employees from factory A results from the 015 test showed that 7 (17.9%) had a tritan (blue-yellow) type of defect and 1 (2.6%) had a complex type of defect. The FM 100 Hue results of factory A employees showed that 51.3% (n=20) had a complex type of defect. Total error scores (TES) calculated from the FM 100 Hue test revealed that employees from factory A had a statistically significant higher mean TES of 65.13:!: 48.31 compared to that of control subjects with a mean TES of 31.26:!: 14.93. For employees in factory B, 10 employees (25.0%) had a tritan (blue-yellow) type of defect and 2 (5.0%) had a complex type of defect. Results of the FM 100 Hue test showed that 4 employees (1.0%) had a tritan type of defect whereas 22 (55.0%) had a complex type of defect. Mean total error scores (TES) calculated from the FM 100 Hue test revealed that employees from factory B had a statistically significant higher mean TES of 71.54 :t 54.63 compared with that of control subjects with a mean TES of 31.26 :t. 14.93
The above results show that employees of the plastic factories studies are associated with a higher risk of acquiring colour vision defects as compared to normal subjects who are not engaged in the plastic manufacturing industry. This may have an implication towards the future retinal health of employees in petrod1emical-based industries.
Introduction: The clinical evaluation of the three layers of tear film is still poorly described. The purpose of this study is to evaluate the value of aqueous assessment in diagnosing dry eye.
Materials and method: Schirmer test with anaesthesia (STA) and tear meniscus height (TMH) measurement were conducted on non-dry eye (NDE) and dry eye (DE) subjects in this cross-sectional study. The NDE and DE subjects were classified using two types of classification; classification 1 and classification 2.
Results: 321 subjects with 642 eyes were recruited in the study. STA was significantly correlated with TMH (r = 0.24, p < 0.001) in all 642 eyes. The comparison between nondry and dry eye subjects in STA and TMH were not significantly different (p > 0.05) if the Classification 1 was used to define dry eye. In Classification 2, there were significantly different between NDE (12.5 ± 8.2 mm) and DE (3.4 ± 0.8 mm) subjects in STA (p < 0.001). Similar trend was also depicted in TMH based on the definition of dry eye stated in Classification 2 (NDE = 0.45 ± 0.20 mm, DE = 0.39 ± 0.14 mm; p < 0.05).
Conclusion: The value of STA and TMH were lower significantly in dry eye subjects. However, the significant outcomes were only demonstrated if the clinical signs of dryness were used in the definition of dry eye.
Introduction: There was no previous study to assess relationship between dry eye symptoms and signs in the local population. The purpose of this study is to evaluate the relationship of symptomatic assessment and clinical signs of dryness in dry eye subjects.
Materials and method: A Cross-sectional study with convenient sampling involving 321 subjects with 642 eyes was done. Subjects were divided into non-dry eye (NDE) and dry eye (DE) groups. The division of NDE and DE groups were done using two types of classification. In Classification 1(symptoms-based), DE was defined if the score of Ocular Surface Disease Index (OSDI) score was more than 33. The value of tear film break-up time (TFBUT) less than 5 seconds and Schirmer test with anaesthesia (STA) less than 5mm/5 minutes were considered as DE for Classification 2 (signs based).
Results: There were poor correlations between OSDI and clinical signs of dryness in all subjects involved (p > 0.05). Similar findings were also noted within NDE subjects in Classification 1 and Classification 2. OSDI score was also not significantly correlated with the signs of dryness within DE subjects except with ocular protection index (OPI) (r = - 0.14, p = 0.047) in Classification 1 and with conjunctival lissamine green staining (CLGS) (r = 0.23, p = 0.040) in Classification 2.
Conclusion: There were no significant correlation between the symptoms of dry eye and the clinical signs of dry eye. Therefore, the clinical diagnosis of dry eye can be made based on either just on the symptoms or the signs.
PURPOSE:This study aimed to determine the relationship between macular thickness and spherical equivalent refraction (SER), axial length (AL) and vitreous chamber depth (VCD) in Malay subjects.
METHODS: Sixty-three subjects (aged 19-24 years) with a mean SER of -1.79 ± 2.24 D, mean axial length of 24.26 ± 1.35 mm and mean vitreous chamber depth of 17.02 ± 1.33 mm were included in this clinical cross-sectional study. Stratus optical coherence tomography (Time Domain optical coherence tomography) was used to determine the thickness of the outer macular (perifovea) and inner macular (parafovea) at four different locations, that is, temporal, superior, nasal and inferior quadrants and also the fovea itself.
RESULTS: Positive correlations were found between the outer macular (perifovea) thickness and SER at the temporal (R = 0.47, p < 0.05), superior (R = 0.36, p < 0.05) and inferior (R = 0.31, p < 0.05) quadrants. Foveal thickness was also positively correlated with AL (R = 0.34, p < 0.05) and VCD (R = 0.32, p < 0.05). Negative correlations were found between outer macular thickness and axial length at the temporal (R = -0.46, p < 0.05), superior (R = -0.27, p < 0.05), nasal (R = -0.25, p < 0.05) and inferior (R = -0.36, p < 0.05) quadrants. Negative correlations were also found between outer macular thickness and VCD at the temporal (R = -0.51, p < 0.05), superior (R = -0.32, p < 0.05), nasal (R = -0.31, p < 0.05) and inferior (R = -0.40, p < 0.05) quadrants.
CONCLUSIONS: This study shows that the degree of myopia and elongation of the globe are associated with thinning of most areas of the perifovea. A trend for foveal thickening in the high myopia group is also inferred, although this does not apply to the low and moderate myopia groups.
Study site: Optometry and ophthalmology clinics, National Institute of Ophthalmic Sciences, Tun Hussein Onn National Eye Hospital (THONEH), Petaling Jaya