Small-aperture intraocular lens tolerance to induced astigmatism

Applications of the pinhole effect in clinical vision science

The pinhole effect is commonly used to discriminate uncorrected refractive error from ocular diseases. A small aperture limits the width of light beams entering the eye, thus increasing the depth of focus. The pinhole effect has also been used in spectacles, contact lenses, corneal inlays, and intraocular lenses (IOLs) to improve reading by compensating for loss of accommodative function. Pinhole spectacles improve near visual acuity, but reduce reading speed, increase interblink interval, and decrease tear break-up time. For contact lenses and IOLs, pinhole devices are usually used in the nondominant eye, which allow compensation of various refractive errors and decrease spectacle dependence. Pinhole corneal inlays are implanted during laser in situ keratomileusis or as a separate procedure. Pinhole IOLs are gaining popularity, particularly as they do not bring a risk of a local inflammatory reaction as corneal inlays do. Disadvantages of using the pinhole effect include high susceptibility to decentration, decrease in retinal luminance levels, and difficulties in performing fundus examinations or surgery in eyes with implanted devices. There are also concerns regarding perceptive issues with different retinal illuminances in the 2 eyes (the Pulfrich effect).

Managing low corneal astigmatism in patients with presbyopia correcting intraocular lenses: a narrative review

Cataract surgery has become a refractive procedure in which emmetropia is the goal, with the implantation of extended depth-of-focus or multifocal intraocular lenses (IOLs) being the commonly selected option to restore vision beyond the far distance. The selection criteria for implanting these lenses can differ from those for monofocal IOLs and even between technologies, as eye characteristics can affect postoperative visual performance. Corneal astigmatism is an eye characteristic that can affect visual performance differently, depending on the implanted IOL. The magnitude of corneal astigmatism, the tolerance of the IOL to this astigmatism, economic aspects, comorbidities, and the efficacy of astigmatism treatment are factors that can make surgeons' doubt as to what astigmatism treatment should be applied to each patient. This review aims to summarize the current evidence related to low astigmatism tolerance in presbyopia-correcting lenses, the efficacy achieved through corneal incisions, and their comparison with the implantation of toric IOLs.

Small Aperture IC-8 Extended-Depth-of-Focus Intraocular Lens in Cataract Surgery: A Systematic Review

The aim of this paper is to evaluate the visual outcomes and patient satisfaction of small aperture IC-8 IOLs in cataract patients with or without prior ocular events. A systematic review of full-length original English studies reporting the visual results of small aperture IC-8 IOL implantation after cataract surgery in three databases, PubMed, Web of Science and Scopus, was performed according to the PRISMA statement. The Quality Assessment Tool for case series studies from the National Heart, Lung, and Blood Institute was used to analyze the quality of the studies selected. The search provided 543 articles, of which 22 were included in this systematic review. Significant improvements in uncorrected distance visual acuity (UDVA); uncorrected intermediate visual acuity (UIVA); uncorrected near visual acuity (UNVA); perception of photic phenomena; and patient satisfaction have been reported. Unilateral and bilateral small aperture IC-8 IOL implantation reduces photic phenomena and provides good vision for all distances with high patient satisfaction and minimal postoperative complications. Therefore, the implantation of this IOL may be recommended for patients with cataracts, corneal irregularities and ocular trauma with partial aniridia.

Presbyopia correction after previous Intracor treatment: Combined implantation of a small-aperture and a non-diffractive extended-depth-of-focus lens

PURPOSE

We present the case of implantation of two different Extended depth of focus intraocular lenses (EDoF IOLs) in a patient with a history of unilateral intrastromal femtosecond laser treatment for presbyopia correction (Intracor).

OBSERVATIONS

The patient reported decreasing visual acuity at near distance and increasing spectacle dependence. Ten years earlier, he had Intracor treatment for presbyopia correction in his left eye. Corrected distance visual acuity (CDVA) was 0.08 logMAR for the right eye and 0.16 logMAR for the left eye. Apart from dysfunctional lens syndrome, the examination results were unremarkable. Phacoemulsification and subsequent IOL implantation was performed in both eyes. The left eye was implanted with an IC-8 (AcuFocus, Irvine, CA, USA), whereas the fellow eye was implanted with an AcrySof IQ Vivity IOL (Alcon, Fort Worth, TX, USA). Postoperatively, CDVA improved to 0.02 and 0.04 logMAR for the right and left eye. Uncorrected intermediate visual acuity (UIVA) was 0.24 logMAR for the right eye and -0.04 logMAR for the left eye, binocular UIVA was -0.04 logMAR. The patient reported a low level of photic phenomena and spectacle independence for far and intermediate distance.

CONCLUSIONS AND IMPORTANCE

Combined implantation of a non-diffractive and a small-aperture EDoF lens after previous unilateral Intracor treatment could successfully improve visual acuity at far and intermediate distance.

Multifocal and Extended Depth-of-Focus Intraocular Lenses in 2020

Ophthalmic surgeons have been overwhelmed by the influx of multifocal intraocular lens (IOL) options in recent years, with close to 100 IOLs on the market in 2020. This practical and technical update on a representative group of established as well as newly launched multifocal IOLs on the market focuses on multifocal IOLs, including extended depth-of-focus lenses. We also describe the optical basis of lens platforms used and thorough preoperative planning to aid decision making. This allows the surgeon the knowledge base to deliver the required relative customized spectacle independence with the least photic phenomenon and loss of contrast possible while achieving high individual patient satisfaction. Data of reviewed IOLs displayed in tabular format include mean monocular uncorrected distance, intermediate, and near visual acuities (logarithm of the minimum angle of resolution), with standard deviations and ranges where available. The range of vision targeted, pupil dependence, toric availability, as well as type of optical platform, are provided as a practical guide to demystify existing terminology on the market that may create interest around a seemingly new design that is actually not novel at all. Halos and glare experienced, levels of patient satisfaction, and spectacle independence achieved also are summarized. A wide range of multifocal IOLs options are available on the market to surgeons. Comprehensive patient selection and examination, combined with knowledge of the most recent options and adequate patient counseling, including neuroadaptation, can avoid dissatisfaction. Many recently available IOLs are awaiting formal results, but the methods by which we label and compare these types of IOLs must also be standardized.

Implantation of a small-aperture intraocular lens and a partial aniridia implant in eyes with traumatic iris defects

Purpose

To report the clinical outcomes after implantation of a small-aperture intraocular lens (IOL) and a partial aniridia ring in three patients with traumatic iris defects.

Observations

The corrected distance visual acuity (CDVA), irregular astigmatism, and glare improved in all patients. In one patient, the monocular defocus curve showed a visual acuity (VA) of 0.30 logMAR or better from 1.0 to −1.5 D, and the halo size and intensity were 5 and 10 (on a scale from 0 to 100), respectively, and the glare size and intensity were 23 and 16 (on a scale from 0 to 100), respectively.

Conclusions and importance

The pinhole effect of the small-aperture IOL helped considerably decrease irregular astigmatism and improve visual acuity. The partial aniridia implant also contributed to the reduction of the glare symptoms, while allowing a sufficient fundus assessment. The combined implantation of the small-aperture IOL and the partial aniridia device, therefore, presents an effective option for improvement of the visual symptoms in patients with traumatic iris defects.

Spectacle Independence in Patients with Prior Radial Keratotomy Following Cataract Surgery: A Case Series

Purpose

To assess if post-keratorefractive patients can achieve spectacle independence following cataract surgery with currently available presbyopia correcting intraocular lenses (IOLs).

Patients and Methods

Retrospective case series of unilateral implantation of the IC-8 IOL in two patients with history of bilateral myopic radial keratotomy (RK) and one patient with history of bilateral myopic RK and astigmatic keratotomy (AK), and bilateral implantation of AT Lisa 939M multifocal IOLs in one patient with previous history of RK and laser in situ keratomileusis (LASIK).

Results

Good uncorrected distance, intermediate and near visual acuity (VA) was achieved for most patients. Stereopsis and contrast sensitivity (CS) were maintained in patients that received the IC-8 IOLs, and two patients achieved full spectacle independence. The patient that received the trifocal lenses expressed satisfaction with their vision, but required long distance correction and experienced reduced CS.

Conclusion

The IC-8 and AT Lisa 939M IOLs both offer satisfactory results and reduced spectacle dependence in post-keratorefractive patients. However, it is recommended to properly counsel visual outcomes and patient expectations before commencing surgery.

Initial Clinical Outcomes of a New Extended Depth of Focus Intraocular Lens

PURPOSE

To evaluate clinical and patient-reported outcomes of a new extended depth of focus intraocular lens (IOL).

METHODS

Data of patients treated between September 2017 and September 2018 who underwent a refractive lens exchange/cataract surgery with an implantation of the AT LARA 829MP IOL (Carl Zeiss Meditec AG, Jena, Germany) and attended the 1-week, 1-month, and 3-month follow-up visit were reviewed.

RESULTS

At 3 months, the percentage of eyes within ±0.50 diopters (D) of emmetropia was 86.7%. The mean binocular uncorrected distance visual acuity was -0.05 ± 0.09 logMAR and the mean binocular unaided near vision was 0.26 ± 0.14 logMAR. Of all patients, 90.3% were satisfied with their vision. The percentage of patients spectacle-free for near and distance vision was 83.6% and 95.4%, respectively. On a scale from 1 (no difficulty) to 7 (severe difficulty), there was an average 1.2 to 1.4 units increase in glare, halo, and starburst between the preoperative and 1-month visit, and a decrease of 0.2 to 0.3 units between the 1- and 3-month visit.

CONCLUSIONS

The new extended depth of focus IOL provided reasonable unaided near and distance vision, as well as spectacle independence and patient satisfaction. Some optical side effects were reported in the early postoperative period. [J Refract Surg. 2019;35(7):426-433.].

Comparison of tolerance to induced astigmatism in pseudophakic eyes implanted with small aperture, trifocal, or monofocal intraocular lenses

Purpose: To compare the effect of induced astigmatic defocus on visual performance in pseudophakic eyes implanted with a small aperture, trifocal, or monofocal intraocular lens (IOL).

Patients and methods: The study included 44 eyes with one of four types of IOL (IC-8 IOL (AcuFocus Inc., USA); FineVision (PhysIOL SA, Belgium); AT Lisa (Carl Zeiss AG, Germany); and enVista monofocal (Bausch & Lomb, USA). For astigmatic tolerance assessment, monocular distance visual acuity was measured with cylindrical lenses (power range=0.00–2.50 diopters (D) in 0.50 D increments) added to the subjects best-corrected distance manifest refraction. The assessment was repeated on three pre-determined axes (90°, 180°, and either 45° or 135°). The magnitude of astigmatic tolerance at each defocus step was assessed by taking the difference between logMAR visual acuity at the defocus step relative to that at 0.0 D (ie, no defocus condition).

Results: Across all three axes, the reduction of mean monocular visual acuity at all defocus levels relative to no defocus was significantly smaller in IC-8 group compared to the other IOL groups. When the data was combined across all axes, the astigmatic tolerance of the IC-8 group was better than AT Lisa group from 0.50 D to 2.50 D and FineVision group from 0.50 D to 1.50 D (all P<0.05, ANOVA). The IC-8 group was better than the enVista group, but not significantly (P>0.05, ANOVA). Among individual orientations, statistically significant differences were seen between IC-8 IOLs and the other IOLs, with the largest difference being in the oblique axis. Astigmatic tolerance at all axes combined was 1.40 D for IC-8 IOL, 0.70 D for AT Lisa and FineVision, and 1.00 D for enVista IOLs.

Conclusion: The small aperture IC-8 IOL showed greater tolerance to induced astigmatic defocus compared to trifocal and monofocal IOLs.