The BHVI-EyeMapper: peripheral refraction and aberration profiles

Widefield wavefront sensor for multidirectional peripheral retinal scanning

The quantitative evaluation of peripheral ocular optics is essential in both myopia research and the investigation of visual performance in people with normal and compromised central vision. We have developed a widefield scanning wavefront sensor (WSWS) capable of multidirectional scanning while maintaining natural central fixation at the primary gaze. This Shack-Hartmann-based WSWS scans along any retinal meridian by using a unique scanning method that involves the concurrent operation of a motorized rotary stage (horizontal scan) and a goniometer (vertical scan). To showcase the capability of the WSWS, we tested scanning along four meridians including a 60° horizontal, 36° vertical, and two 36° diagonal scans, each completed within a time frame of 5 seconds.

Dynamic opto-mechanical eye model with peripheral refractions

Many myopia control methods based on the peripheral defocus theory have emerged towards applications in recent years. However, peripheral aberration is a critical issue, which is still not well-addressed. To validate the aberrometer for peripheral aberration measurement, a dynamic opto-mechanical eye model with a wide visual field is developed in this study. This model consists of a plano-convex lens representing cornea (f' = 30 mm), a double-convex lens representing crystalline lens (f' = 100 mm), and a spherical retinal screen with a radius of 12 mm. To optimize the quality of spot-field images from the Hartman-Shack sensor, the materials and surface topography for the retina are studied. The model has an adjustable retina to achieve Zernike 4th item (Z4 focus) ranging from -6.28 µm to +6.84 µm. As for mean sphere equivalent, it can achieve -10.52 D to +9.16 D at 0° visual field and -6.97 D to +5.88 D at 30° visual field with a pupil size of 3 mm. To realize a changing pupil size, a slot at the back of the cornea mount and a series of thin metal sheets with 2, 3, 4, and 6 mm holes are generated. Both on-axis aberrations and peripheral aberrations of the eye model are verified by a well-used aberrometer and the eye model to mimic a human eye in a peripheral aberration measurement system is illustrated.

Central and Peripheral Ocular High-Order Aberrations and Their Relationship with Accommodation and Refractive Error: A Review

High-order aberrations (HOAs) are optical defects that degrade the image quality. They change with factors such as pupil diameter, age, and accommodation. The changes in optical aberrations during accommodation are mainly due to lens shape and position changes. Primary spherical aberration (Z(4.0)) is closely related to accommodation and some studies suggested that it plays an important role in the control of accommodation. Furthermore, central and peripheral HOAs vary with refractive error and seem to influence eye growth and the onset and progression of myopia. The variations of central and peripheral HOAs during accommodation also appear to be different depending on the refractive error. Central and peripheral high-order aberrations are closely related to accommodation and influence the accuracy of the accommodative response and the progression of refractive errors, especially myopia.

Dual-angle open field wavefront sensor for simultaneous measurements of the central and peripheral human eye

We have developed a novel dual-angle open field wavefront sensor. This device captures real-time foveal and peripheral Zernike aberrations, while providing natural binocular viewing conditions for the subjects. The simultaneous data recording enables accurate analysis of changes in ocular optics with accommodation overcoming any uncertainties caused by accommodative lag or lead. The instrument will be used in myopia research to study central and peripheral ocular optics during near work and to investigate the effects of optical myopia control interventions. Proof of concept measurements, performed on an artificial eye model and on 3 volunteers, showed good repeatability with foveal-peripheral data synchronization of 65 msec or better. The deviations from subjective cycloplegic refractions were not more than 0.31 D. Furthermore, we tested the dual-angle wavefront sensor in two novel measurement schemes: (1) focusing on a close target, and (2) accommodation step change.

Peripheral refraction and spherical aberration profiles with single vision, bifocal and multifocal soft contact lenses

PURPOSE

To compare the peripheral refraction and spherical aberration profiles along three visual field meridians of 16 commercial single vision (SV), bifocal (BF) and multifocal (MF) test contact lenses with a single vision control.

METHOD

Forty-four participants [24.2±2.4 years, SE: -0.50 to -4.50D] were randomly fitted, contra-laterally, with 6 SV's [Air Optix Aqua (control), Acuvue Oasys, Biofinity, Clariti, Night & Day and Proclear], 3 BF's [Acuvue Bifocal low and high add, MiSight] and 8 MF's [Proclear D & N in 1.5 and 2.5D adds; AirOptix, PureVision low & high adds]. Peripheral refraction was performed across horizontal, oblique and vertical meridians, with lenses on eye using the BHVI-EyeMapper. The power vectors M, J₀, J₄₅ and the spherical aberration coefficient were analysed. The peripheral refraction and aberration profiles of the test lenses were compared with the profiles of the control lens using curvature and slope coefficients.

RESULTS

Compared to the control, a relative peripheral hyperopic shift (M), a less negative J₀ curvature coefficient along the horizontal meridian, a less positive J₀ curvature coefficient along the vertical meridian, a less negative J₄₅ curvature coefficient along the oblique meridian and a more positive spherical aberration curvature coefficient along most meridians was seen with the Acuvue Bifocal and all center-near multifocal lenses. For the center-distance multifocal lenses the direction of the curvature coefficients of the same refraction and aberration components was opposite to that of the center-near lenses. The greatest differences in the slope coefficients when compared to the control were found for the Acuvue Bifocal lenses and all multifocal contact lenses for the refractive component M and the spherical aberration coefficient along the horizontal visual field meridian, with the Acuvue Bifocal and the center-near multifocal lenses having more positive coefficients and the center-distance lenses having more negative coefficients.

CONCLUSION

When worn on eye, different commercially available lens types produce differences in the direction and magnitude of the peripheral refraction and spherical aberration profiles along different visual field meridians. This information may be relevant to refractive development and myopia control.

IMI - Clinical Myopia Control Trials and Instrumentation Report

The evidence-basis based on existing myopia control trials along with the supporting academic literature were reviewed; this informed recommendations on the outcomes suggested from clinical trials aimed at slowing myopia progression to show the effectiveness of treatments and the impact on patients. These outcomes were classified as primary (refractive error and/or axial length), secondary (patient reported outcomes and treatment compliance), and exploratory (peripheral refraction, accommodative changes, ocular alignment, pupil size, outdoor activity/lighting levels, anterior and posterior segment imaging, and tissue biomechanics). The currently available instrumentation, which the literature has shown to best achieve the primary and secondary outcomes, was reviewed and critiqued. Issues relating to study design and patient selection were also identified. These findings and consensus from the International Myopia Institute members led to final recommendations to inform future instrumentation development and to guide clinical trial protocols.

Vision Performance and Accommodative/Binocular Function in Children Wearing Prototype Extended Depth-of-Focus Contact Lenses

OBJECTIVE

To assess two prototype contact lenses (CLs) that extend depth of focus through deliberate manipulation of multiple spherical aberration terms (extended depth-of-focus [EDOF]) for visual performance, accommodative and binocular function, and objective static near refraction against a single-vision (SV) CL.

METHOD

This was a prospective, randomized, cross-over, single-masked (participant) clinical trial in which 16 myopic children wore 2 prototype CLs (EDOFL/EDOFH) designed for presbyopes and a SV CL, each for one week. Measurements comprised monocular and binocular high-contrast visual acuity (HCVA: 6 m, 40 cm), binocular low-contrast visual acuity (LCVA: 6 m), contrast sensitivity (CS: 6 m), phorias (3 m, 33 cm), monocular-accommodative facility (33 cm), and objective static refraction (spherical equivalent M) at zero, -3, and -5 D vergences. Measurements were taken 10 min after lens insertion. Subjective response was assessed using take-home questionnaires comprising vision clarity (distance/intermediate/near), vision quality (haloes at night/ghosting), vision stability when moving (playing sport/using stairs), and comfort.

RESULTS

Single vision was significantly better than both EDOF CLs for monocular HCVA, LCVA, and CS (6 m); vision clarity (distance), ghosting (P≤0.040), and EDOFL for binocular HCVA (6 m, P=0.047). M was significantly closer to the ideal objective static refraction at -3 and -5 D vergences (P≤0.004) with both EDOF compared with SV CLs. There were no differences between CLs for any other variable (P≥0.169).

CONCLUSION

Extended depth-of-focus CLs caused minimal disruption to the accommodative and binocular system compared with SV CLs when worn by myopic children. Future EDOF designs for children should reduce the difference between SV for distance vision and vision quality while maintaining the same performance for intermediate and near.

Effect of cylinder power and axis changes on vision in astigmatic participants

PURPOSE

To ascertain the impact of altering cylinder (cyl) power and axis on vision in astigmatism.

METHODS

In a prospective, randomized, participant-masked, crossover clinical trial, 28 astigmatic participants were tested for the following conditions on different days: full sphero-cyl correction and undercorrection by 0.25, 0.50, and 0.75 DC while maintaining spherical equivalence. Axis was also misaligned between -30° and +30°, in 10° steps. For each configuration, monocular high- and low-contrast visual acuities (HCVA, LCVA) were measured at 6 m, and participants rated vision clarity (1-10), vision satisfaction (1-10), and vision acceptability (yes/no). Linear mixed models were used to compare visual performance in the overall group and in low, medium, and high cyl subgroups.

RESULTS

Undercorrecting cyl power affected all groups equally (P≥0.073). Undercorrection by 0.75 DC was significantly different to full cyl power for all variables (P≤0.007), while 0.25 DC undercorrection did not cause any significant decreases (P>0.05). Undercorrection by 0.50 DC was significantly different to full cyl power for HCVA (P=0.006, however not clinically significant) and vision acceptability (P=0.034). Axis misalignment affected the cyl groups differently (P<0.001), with the greatest impact in the high cyl group, followed by the medium then the low-cyl group. Misalignment by ±30° caused significant decreases in almost all cases (P≤0.003), while misalignments by ±10° or ±20° caused significant decreases for some cyl groups and test variables.

CONCLUSION

Undercorrection of cyl by ≤0.50 DC while maintaining spherical equivalence has no significant effect on HCVA, LCVA, vision clarity, and vision satisfaction, while the amount of axis misalignment that can be tolerated is dependent on the cyl power. These results may have practical ophthalmic applications, such as reducing the total number of stock keeping units of toric contact lenses.

Short-Term Adaptation of Accommodative Responses in Myopes Fitted With Multifocal Contact Lenses

OBJECTIVES

To investigate whether adaptation of accommodative responses occurred in non-presbyopic myopes fitted with four multifocal contact lens (MFCL) designs.

METHODS

Prospective, subject-masked clinical investigation comprising 40 experienced myopic lens wearers (18-25 years) fitted bilaterally with single-vision (SV) control lens (Air Optix Aqua [Alcon, Fort Worth, TX]) and randomized to two of four test MFCL (Proclear MFCL [Distance and Near] [CooperVision, Pleasanton, CA], Air Optix Aqua MFCL, Purevision MFCL [Bausch & Lomb, Rochester, NY]). Lenses were dispensed on a daily wear basis and worn for a minimum of 8 (maximum 14) days over three assessment visits, with a 1-week wash out between stages. Paraxial curvature matched spherical equivalent (M) was measured with lenses on eye using the BHVI-EyeMapper with an internal movable fixation target positioned at target vergences of +1.00 diopter (D) (fogging) and -2.00 to -5.00 in 1.00 D steps (accommodative stimuli). Accommodative facility was assessed by several flips of ±2.00 D/min (cycles/min) at 33 cm and horizontal phoria with a Howell phoria card at distance (3 m) and near (33 cm).

RESULTS

For center-distance MFCL (Proclear D), the spherical equivalent (M) at all near vergences became significantly more negative at the follow-up visits compared with the dispensing visit (P<0.029). For all center-near MFCLs and SV lens, M remained invariant during the adaptation period, however (P≥0.267). At distance, M became significantly less minus with Air Optix Aqua MFCL over time (P=0.049). Accommodative facility increased over the three assessment visits for participants wearing Air Optix Aqua SV, Air Optix Aqua MFCL, and PureVision MFCL (P=0.003). Distance and near horizontal phoria remained stable over the three assessment visits for all lens types (P≥0.181).

CONCLUSIONS

Adaptation differences were not consistently found for static accommodative measures gauged by M, as measured with lenses on eye, and phoria but were found in dynamic measures (facility), perhaps indicating some learning effects. Accommodative adaptation seems unlikely to occur with long-term MFCL in non-presbyopes.

Relative peripheral refraction across 4 meridians after orthokeratology and LASIK surgery

Background

To characterize the axial and off-axis refraction across four meridians of the retina in myopic eyes before and after Orthokeratology (OK) and LASIK surgery.

Methods

Sixty right eyes with a spherical equivalent (M) between − 0.75 to − 5.25 D (cylinder <− 1.00 D) underwent LASIK (n = 26) or OK (n = 34) to treat myopia. Axial and off-axis refraction were measured with an open-field autorefractometer before and after stabilized treatments. Off-axis measurements were obtained for the horizontal (35° nasal and temporal retina) and vertical (15° superior and inferior retina) meridians, and for two oblique directions (45–225° and 135–315°) up to 20° of eccentricity. The refractive profile was addressed as relative peripheral refractive error (RPRE).

Results

OK and LASIK post-treatment results showed an increase of myopic relative refraction at several eccentric locations. At the four meridians evaluated, the M component of the pre-treatment RPRE values was not statistically different (p > 0.05) from the post-treatment RPRE within 30° and 20° of the central visual field after LASIK and OK, respectively. These results demonstrated that the treatment zone warrants an optimal central field of vision.

Conclusions

The present study gives an overview of RPRE after refractive corneal reshaping treatments (OK and LASIK) across vertical, horizontal and two oblique meridians together. This allows a 3D representation of RPRE at the retina and shows that the myopic shift induced by both treatments is more relevant in horizontal directions.

Effects of relative negative spherical aberration in single vision contact lens visual performance

OBJECTIVE

The study aimed to compare the visual performance of contact lenses with and without negative spherical aberration (SA) over 5 days of wear.

METHODS

At baseline, 32 myopic participants (aged 18-33 years) were fitted in a randomized order with two lenses (test lens with minimal or no SA and 1-Day Acuvue Moist designed with negative SA) for 5 days (minimum 6 hours wear/day). Participants returned for a follow-up visit. This consisted of on-axis SA measurements; high- and low-contrast visual acuities at 6 m; high-contrast acuities at 70 and 40 cm; low-illumination, low-contrast acuity at 6 m; stereopsis at 40 cm; horizontal phorias at 3 m and 33 cm; and ±2.00 D monocular accommodative facility at 33 cm. Participants also rated (1-10 scale) vision quality (clarity and lack of ghosting for distance, intermediate, near, driving vision and vision stability during day- and night-time), overall vision satisfaction, ocular comfort, and willingness to purchase (yes/no response).

RESULTS

1-Day Acuvue Moist induced significantly (p<0.05) more negative SA at distance (Δ=0.078 μm) and near (Δ=0.064 μm) compared to the test lens, for a 6 mm pupil. There were no significant differences (p>0.05) in acuity, binocular vision, and all subjective metrics except vision stability between lenses where the test lens was rated to provide more stable vision (p<0.05).

CONCLUSION

Contrary to expectations, incorporating negative SA in single vision soft contact lenses did not improve visual performance in non-presbyopic adult myopes.

Peripheral Refraction and Aberration Profiles with Multifocal Lenses

SIGNIFICANCE

The amount of central or peripheral myopic shift, as induced by different multifocal contact lenses when viewing objects at distance or near, may provide insights on the potential efficacy for slowing eye growth.

PURPOSE

The present study aims to compare peripheral refraction and higher-order aberration profiles of four multifocal contact lenses with a single vision control lens.

METHODS

Thirty-five myopes (age 21.2 ± 2.1 years) completed the trial, of whom 16 wore Air Optix Aqua and Proclear Multifocal Distance and Near (Group 1, spherical equivalent: -2.90 ± 0.95D), whereas 19 wore Air Optix Aqua, Air Optix Multifocal, and PureVision Multifocal (Group 2, spherical equivalent: -2.95 ± 0.78D). Refraction and aberration profiles with lenses were measured using the BHVI-EyeMapper with (-2.00 to -5.00D in 1.00D steps) and without (+1.00D fogging) accommodation. Data were quantified using M2/4 (2nd and 2nd + 4th order), J0, J45, and higher-order aberration coefficients coma C[3, 1] and spherical aberration C[4, 0].

RESULTS

The center-distance lens exhibited a relative peripheral myopic shift in M2/4 and J0, positive on-axis C[4, 0], negative on-axis C[3, 1] and on-axis M4 was less negative for accommodative demands ≤-3.00D (P < .05). Inversely, the center-near lenses showed a relative peripheral hyperopic shift in M2/4 and J0, negative on-axis C[4, 0], positive on-axis C[3, 1] and on-axis M4 was more negative for demands of -2.00 and -3.00D (P < .05). Independent of lens type, relative peripheral M4 significantly decreased during accommodation. Accounting for C[4, 0], a greater change in relative M profiles and accommodative responses was found for multifocal lenses.

CONCLUSIONS

Based on the hypothesis that myopic retinal defocus counters eye growth, center-near multifocal lenses exhibited the preferred on-axis features, i.e., producing a central myopic shift at near compared to the control. The center-distance lens exhibited preferred off-axis features, producing relative peripheral myopia, which increased further during accommodation.

Impact of Spherical Aberration Terms on Multifocal Contact Lens Performance

PURPOSE

To investigate the impact of the primary (PSA) and secondary (SSA) spherical aberration terms on visual performance (VP) in presbyopes, as measured using multifocal (MFCL) soft contact lenses on eye.

METHODS

Seventeen presbyopes (age: 55.1 ± 6.9 years) wore seven commercial lenses (four center-near (MFCL N), one center-distance (MFCL D), one bifocal, and one single vision control). Unaided and with each lens on eye, the PSA and SSA terms were obtained with an aberrometer, the BHVI-EyeMapper (low illumination, natural and 4 mm pupil diameter). High- and low-contrast distance visual acuity, contrast sensitivity, high-contrast visual acuities at near, and range of clear vision were measured. In addition, subjective VP variables included clarity of vision at distance and near, ghosting, and overall vision satisfaction. Pearson's correlation was used to determine the association between the PSA and SSA terms and the VP variables.

RESULTS

PSA (natural pupil) was more negative (P < .05) with the MFCL N (mean PSA = -0.053 ± 0.080 μm) and bifocal (PSA = +0.005 ± 0.067 μm) lenses and more positive with the MFCL D lens (PSA = +0.208 ± 0.160 μm) than the control (+0.067 ± 0.072 μm). SSA (natural pupil) was significantly more positive for the MFCL N lenses (mean SSA = +0.025 ± 0.029 μm) compared to the control (SSA = -0.001 ± 0.017 μm). PSA and SSA terms were significantly (P < .05) correlated with 78% and 56% of VP variables, respectively, but the correlation coefficients were weak, ranging between |0.210| and |0.334|. Although distance variables showed improved VP with more positive PSA or negative SSA, most near variables showed improved VP with more negative PSA. Range of clear focus was greater for more negative PSA terms.

CONCLUSIONS

The amount and direction of PSA and SSA terms, as measured with different MFCLs on eye, can affect VP at different distances. Results of this study may provide useful information when designing new or optimize existing MFCLs for improved VP at specific distances.

Peripheral aberrations in adult hyperopes, emmetropes and myopes

PURPOSE

To determine differences in peripheral aberrations in hyperopic, emmetropic and myopic groups.

METHODS

Cycloplegic peripheral aberrations for 5 mm pupils were measured at 39 locations across 42° × 32° of right eye visual fields with a COAS-HD Hartmann-Shack aberrometer in nine hyperopes (mean age 29 ± 5 years, spherical equivalent refraction M + 1.47 ± 0.58 D), 20 emmetropes (28 ± 7 years, +0.06 ± 0.36 D) and 20 myopes (27 ± 6 years, -2.55 ± 1.82 D). Relative peripheral refraction error RPRE and 3rd-4th order Zernike coefficients were compared between the groups.

RESULTS

Hyperopes and emmetropes had relative peripheral myopia across the visual field, with considerable nasal-temporal asymmetry for both groups and superior-inferior asymmetry for hyperopes. Myopes had minimal RPRE along the horizontal meridian, but myopic RPRE along the vertical meridian which was less than the other groups. There was little difference between groups in astigmatic components or higher-order Zernike coefficients, except for fourth-order spherical aberration which was more positive in hyperopes than in both emmetropes (mean difference ±95% CI = +0.05 ± 0.05 μm, p = 0.03) and myopes (+0.07 ± 0.04 μm, p = 0.003). Coma changed rapidly across the visual field with similar rates for all groups.

CONCLUSIONS

Hyperopes and emmetropes had greater relative peripheral myopia than myopes. There was asymmetry in RPRE along the vertical meridian for hyperopes which was not present in the emmetropes, suggesting there may be asymmetries in peripheral eye length along the vertical meridian for the former. Higher-order aberrations were affected by field eccentricity, but refractive error affected only the spherical aberration coefficient, which was more positive for hyperopes than for other groups.

Peripheral Refraction Validity of the Shin-Nippon SRW5000 Autorefractor

PURPOSE

To investigate the operation of the Shin-Nippon/Grand Seiko autorefractor and whether higher-order aberrations affect its peripheral refraction measurements.

METHODS

Information on instrument design, together with parameters and equations used to obtain refraction, was obtained from a patent. A model eye simulating the operating principles was tested with an optical design program. Effects of induced defocus and astigmatism on the retinal image were used to calibrate the model eye to match the patent equations. Coma and trefoil were added to assess their effects on the image. Peripheral refraction of a physical model eye was measured along four visual field meridians with the Shin-Nippon/Grand Seiko autorefractor SRW-5000 and a Hartmann-Shack aberrometer, and simulated autorefractor peripheral refraction was derived using the Zernike coefficients from the aberrometer.

RESULTS

In simulation, the autorefractor's square image was changed in size by defocus, into rectangles or parallelograms by astigmatism, and into irregular shapes by coma and trefoil. In the presence of 1.0 D oblique astigmatism, errors in refraction were proportional to the higher-order aberrations, with up to 0.8 D sphere and 1.5 D cylinder for ±0.6 μm of coma or trefoil coefficients with a 5-mm-diameter pupil. For the physical model eye, refraction with the aberrometer was similar in all visual field meridians, but refraction with the autorefractor changed more quickly along one oblique meridian and less quickly along the other oblique meridian than along the horizontal and vertical meridians. Simulations predicted that higher-order aberrations would affect refraction in oblique meridians, and this was supported by the experimental measurements with the physical model eye.

CONCLUSIONS

The autorefractor's peripheral refraction measurements are valid for horizontal and vertical field meridians, but not for oblique field meridians. Similar instruments must be validated before being adopted outside their design scope.

Association between multifocal soft contact lens decentration and visual performance

PURPOSE

The aim of this study was to assess the association between decentration of several commercial multifocal soft contact lenses (MFCLs) and various objective and subjective visual performance variables in presbyopic and non-presbyopic participants.

MATERIALS AND METHODS

All presbyopic (age >40 years, near add ≥+1.25 D) and non-presbyopic (age ≥18 years, no near add requirements, spherical equivalent ≤-0.50 D) participants were each fitted bilaterally with six and two MFCLs (test lens), respectively, and with one single vision lens (control lens). Lens decentration, ie, the x- and y-differences between the contact lens and pupil centers, was objectively determined. Third-order aberrations were measured and compared. Visual performance (high- and low-contrast acuities and several subjective variables) was analyzed for any associations (Pearson's correlation, r) with MFCL decentration.

RESULTS

A total of 17 presbyopic (55.1±6.9 years) and eight non-presbyopic (31.0±3.3 years) participants completed the study. All lenses displayed a temporal-inferior decentration (x=-0.36±0.29 mm, y=-0.28±0.28 mm, mean ± SD). Compared to the control, a significant inferior decentration was found for the Proclear® MFCL Near lens in both groups (ypresbyopic =-0.26 mm, ynon-presbyopic =-0.70 mm) and for the Proclear® MFCL Distance lens in the non-presbyopic group (ynon-presbyopic =-0.69 mm). In both groups, lens-induced vertical coma (C(3, -1)) was, by at least tenfold, significantly more positive for the Proclear® MFCL Distance lens and significantly more negative for the Proclear® MFCL Near lens. In the presbyopic group, the correlation of total MFCL decentration with vision variables was weak (r<|0.191|). Conversely, a moderate but significant correlation with total MFCL decentration was found in the non-presbyopic group for most of the vision variables, indicating a decrease in vision as decentration increased.

CONCLUSION

Certain MFCLs decentered more than others; the same lens designs also induced significant amounts of third-order aberrations. An association between MFCL decentration and seven out of nine vision variables was found in the non-presbyopic group, ie, the group where lenses were most decentered, which had larger pupils and lower levels of inherent third-order aberrations.

Peripheral refraction and higher-order aberrations with cycloplegia and fogging lenses using the BHVI-EyeMapper

PURPOSE

To determine if a fogging lens ameliorates accommodative effects driven by the closed-view design of the BHVI-EyeMapper (EM) instrument. We compared cycloplegic refraction and higher-order aberration measurements of the EM with those obtained with a fogging lens.

METHODS

Twenty-six, young, participants (15F, 25±5 years, range: 18-35 years, SE: +0.25 D and -3.50 D) with good ocular health were recruited. Five independent measurements of on- and off-axis refraction and higher-order aberrations were recorded across the horizontal visual field, under two conditions: non-cycloplegic measurements with +1.00 D fogging lens and cycloplegia, always in the same sequence. The contralateral eye was occluded during the measurements. Two drops of 1% Tropicamide delivered within 5 min facilitated cycloplegic measurements. All participants were refracted 30 min after installation of the second drop.

RESULTS

Mean spherical equivalent measures of the non-cycloplegic condition were significantly more myopic than their cycloplegic counterparts (p<0.05); approximately by 0.50 D centrally, increasing to 1.00 D towards the periphery. The horizontal astigmatic component, J180, demonstrated small but statistically significant differences between the test conditions. Differences were predominant for eccentricities greater than 30°, in both nasal and temporal meridians. The oblique astigmatic component, J45, was not significantly different between the test conditions. The primary spherical aberration coefficient C(4, 0) was significantly less positive for the non-cycloplegic state than its cycloplegic counterpart. This result held true across the entire horizontal visual field. The horizontal coma and trefoil coefficients C(3, 1) and C(3, 3) were not significantly different between the two conditions.

CONCLUSIONS

The use of +1.00 D fogging lens without cycloplegia did not provide complete relaxation of accommodation. The discrepancies between cycloplegic and non-cycloplegic EM measurements were found to be more pronounced for peripheral field angles than central measures, for both M and J180 components.