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Addition lens alleviates reading-induced ocular stress
Camus K Choy1, Andrew W Siu, Frankie Y Lam
1Department of Optometry and Radiography, Hong Kong Polytechnic University, Hung Hom, Hong Kong, China.
Clinical & Experimental Optometry
|December 11, 2002
Summary
Reading can cause eye strain, leading to increased exophoria. Adding plus lenses during near tasks reduced this eye strain in a dose-dependent manner, suggesting a potential therapeutic benefit.
Area of Science:
- Ophthalmology
- Optometry
- Vision Science
Background:
- Near work is linked to binocular stress, a potential factor in myopia development.
- Understanding the impact of accommodation on reading-induced heterophoria is crucial for eye health.
Purpose of the Study:
- To investigate how accommodation affects near heterophoria induced by reading.
- To evaluate the efficacy of different plus lens additions in mitigating reading-induced eye strain.
Main Methods:
- 22 young adults underwent a 30-minute reading task at 33 cm.
- Near heterophoria was measured before and after reading with 0.00 D, +1.50 D, or +3.00 D addition lenses.
- Changes in heterophoria (exophoric shift) were recorded for each lens condition.
Main Results:
- Reading without added lenses (plano) significantly increased near heterophoria towards exo-deviation (3.81 PD).
- A +3.00 D lens addition markedly reduced the exophoric shift (1.36 PD).
- A +1.50 D lens also reduced the shift (3.14 PD), though not to a statistically significant degree compared to the control.
Conclusions:
- Close work can induce eye strain through extraocular muscle activity, manifesting as exophoria.
- Plus lens incorporation into optical correction offers a power-dependent reduction in this visual stress.
- Further research is needed to confirm the role of binocular stress in myopia and the effectiveness of addition lens therapy.