Clinical applications of wavefront refraction

Abstract

Purpose: To determine normative reference ranges for higher-order wavefront error (HO-WFE), compare these values with those in common ocular pathologies, and evaluate treatments.

Methods: A review of 17 major studies on HO-WFE was made, involving data for a total of 31,605 subjects. The upper limit of the 95% confidence interval (CI) for HO-WFE was calculated from the most comprehensive of these studies using normal healthy patients aged 20 to 80 years. There were no studies identified using the natural pupil size for subjects, and for this reason, the HO-WFE was tabulated for pupil diameters of 3 to 7 mm. Effects of keratoconus, pterygium, cataract, and dry eye on HO-WFE were reviewed and treatment efficacy was considered.

Results: The calculated upper limit of the 95% CI for HO-WFE in a healthy normal 35-year-old patient with a mesopic pupil diameter of 6 mm would be 0.471 μm (471 nm) root-mean-square or less. Although the normal HO-WFE increases with age for a given pupil size, it is not yet completely clear how the concurrent influence of age-related pupillary miosis affects these findings. Abnormal ocular conditions such as keratoconus can induce a large HO-WFE, often in excess of 3.0 μm, particularly attributed to coma. For pterygium or cortical cataract, a combination of coma and trefoil was more commonly induced. Nuclear cataract can induce a negative spherical HO-WFE, usually in excess of 1.0 μm.

Conclusions: The upper limit of the 95% CI for HO-WFE root-mean-square is about 0.5 μm with normal physiological pupil sizes. With ocular pathologies, HO-WFE can be in excess of 1.0 μm, although many devices and therapeutic and surgical treatments are reported to be highly effective at minimizing HO-WFE. More accurate normative reference ranges for HO-WFE will require future studies using the subjects' natural pupil size.

FIGURE 1

Keratoconus in the right eye of a 20-year-old man. (A) Corneal topography map showing an apical power of 65 diopters. (B) HO-WFE map for a 6-mm pupil, with total higher order, 2.928 μm; total coma, 2.087 μm; total spherical, 0.870 μm; and total trefoil, 1.744 μm. The HO-WFE is significantly abnormal in relation to the keratoconus.

FIGURE 2

Pterygium in the left eye of a 42-year-old woman. (A) Anterior eye image. (B) HO-WFE map for a 6-mm pupil, with total higher order, 2.648 μm; total coma, 1.202 μm; total spherical, 0.223 μm; and total trefoil, 2.149 μm. The HO-WFE is significantly abnormal owing to the pterygium.

FIGURE 3

Moderate nuclear sclerosis cataract in the left eye of a 45-year-old woman. The patient had experienced a −8.00-diopter myopic shift in 2 years, with best-corrected acuity of 20/70 (pinhole 20/40). (A) Anterior eye image. (B) HO-WFE map for a 6-mm pupil, with total higher order, 1.505 μm; total coma, 0.521 μm; total spherical, −0.893 μm; and total trefoil, 1.059 μm. The WFE is significantly abnormal owing to the cataract.

FIGURE 4

Anterior cortical cataract in the left eye of a 72-year-old female patient, with best-corrected acuity of 20/70. (A) Anterior eye image. (B) HO-WFE map for a 6-mm pupil, with total higher order, 1.572 μm; total coma, 0.099 μm; total spherical, 0.121 μm; and total trefoil, 1.528 μm. The WFE is significantly abnormal, mainly attributed to trefoil.