Evaluation of visual performance and vision questionnaires in intraocular lens implantation and laser refractive surgery

  • Emmanuel Pazo

Student thesis: Doctoral Thesis


The anterior refractive segment comprises the tear film (TF), cornea and lens. This composite of structures primarily contributes to the refractive power and the quality of vision (QOV). Postoperative small incision lenticule extraction had significantly better and expedient corneal surface physiology recovery than femtosecond laser-assisted laser in situ keratomileusis patients; thereby enhancing their QOV scores. Postoperative tear lipid measurements correlated with postoperative glare and fluctuating vision. Further research is needed to explore other preoperative TF parameters.

Functional vision is a binocular function; however, clinical assessment of vision is routinely monocular. This dichotomy to some degree confounds the subjective questionnaire assessments. Pupil size (PS) has a direct influence upon light and aberration entering the eye. Moreover, diffraction of light can be induced iatrogenically by refractive surgeries, intra- and extraocular implants and ageing. The major factor found to impact the QOV in an asymmetric multifocal intraocular lens (IOL) was preoperative PS and visual axis eccentricity (angle kappa). Since PS generally decreases with age, a larger preoperative pupil ensures that postoperatively there is adequate exposure of the IOL.

Corneal cross-linking (CXL) is a well-accepted treatment for keratoconus. Transepithelial phototherapeutic keratectomy (trans-PTK) can remove the epithelium and smoothen the anterior cornea. Nine-month follow-up of trans-PTK and CXL procedures showed benefits of improved visual acuity and stabilisation of KC at ninemonths follow-up.

Since the 1980’s vision-related quality of life (VR-QOL) questionnaires have been explored to capture and measure this concept. The results demonstrate that VR-QOL questionnaire performs better than VF-14 questionnaire with less variability in the mean range scores. This suggests that the customisable items of VR-QOL questionnaire is better at assessing the individuals VR-QOL.

This body of work demonstrates the impact of these pathologies and anatomical variations upon VA, QOV and VR-QOL. These findings should help guide clinicians preoperatively stratify and postoperatively manage patients.
Date of AwardSept 2017
Original languageEnglish
SupervisorAndrew Nesbit (Supervisor) & Tara Moore (Supervisor)

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