Efficacy of multifocal soft contact lens on asthenopic orthophoric and esophoric myopes with lag of accommodation

Student thesis: Doctoral ThesisOphthalmic Doctorate

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Authors

Chee Horng Ong

Research units

Abstract

The primary aim of this study was to investigate the effectiveness of multifocal soft contact lenses (MFSCLs) in alleviating asthenopic symptoms in symptomatic, orthophoric and esophoric myopes with lag of accommodation by using clinical methods that are commonly used in general practice. Also, whether the amount of MFSCL addition differentially modifies symptoms of asthenopic individuals was assessed.
This study found that Convergence Insufficiency Symptom Survey (CISS) score improved after wearing MFSCLs, when comparing to spectacle (SPECT) and single vision contact lenses (SVCLs). There was no significant difference between the symptom score of multifocal low add (LAMFCLs) and high add contact lenses (HAMFCLs), implying that varying the amount of near addition did not improve the symptom score. Accommodative lag was not significantly improved with MFSCLs. Distant esophoric shift was observed when changing from SPECT to SVCLs and HAMFCLs. Near esophoric shift was found to be lower for both MFSCLs when compared to SVCLs.
Accommodation response changes with MFSCLs wear after a period of one month were also studied. Amplitude of accommodation (AoA) and near point of convergence (NPC) was improved while wearing MFSCLs. Increased positive relative accommodation (PRA) and decreased negative relative accommodation (NRA) was observed while wearing HAMFCLs. No adaptation effect was observed after one month of wearing MFSCLs.
One hundred Singapore optometrists were surveyed, and it was found that 75% were seeing asthenopic patients, with the most common symptoms being tired eyes. Ophthalmic lenses were the most commonly prescribed treatment and had a high success rate. The majority (69%) of the surveyed optometrists have not considered the use of MFSCLs as a treatment option.
In conclusion, this study presented novel findings showing that MFSCLs are effective in relieving asthenopic symptoms. The study finding also suggested that pre-presbyopic individuals do not use the near addition power provided by MFSCLs to replace their accommodative activity, and that MFSCLs do not create a significant change in the phoric status at near. Further work is required to determine whether the improvement in asthenopic symptoms with MFSCLs is contributed by negative SA.

Details

Original languageEnglish
Awarding Institution
Supervisors/Advisors
Award date29 May 2018

    Keywords

  • asthenopia, multifocal, myopes, orthophoric, esophoric, accommodation, contact lenses, spherical aberration

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