The surgical correction of moderate hypermetropia: the management controversy

Comparison of Visual Outcomes and Higher-order Aberrations Between FS-LASIK and SMI-LIKE for Moderate to High Hyperopia: A 2-Year Result

PURPOSE

The aim of the study was to evaluate and compare the long-term visual outcomes and higher-order aberrations (HOAs) between femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and small-incision lenticule intrastromal keratoplasty (SMI-LIKE) in the correction of moderate to high hyperopia.

METHODS

In this study, 16 subjects (20 eyes) underwent FS-LASIK and 7 subjects (10 eyes) underwent SMI-LIKE. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction, mean keratometry (Km), anterior asphericity (Q), and HOAs preoperatively and 2 years postoperatively were obtained in both procedures.

RESULTS

The efficacy indices of the FS-LASIK group and the SMI-LIKE group were 0.85 ± 0.14 and 0.87 ± 0.17, respectively. The safety indices of the FS-LASIK and SMI-LIKE groups were 0.99 ± 0.15 and 1.08 ± 0.24, respectively. No significant difference in safety index or efficacy index was found between the FS-LASIK and SMI-LIKE groups (all P > 0.05). The correlation coefficient of the attempted versus achieved spherical equivalent postoperatively was 0.69 ( P < 0.01) and 0.89 ( P < 0.01) in the FS-LASIK group and SMI-LIKE groups, respectively. The front Km, negative Q value, negative spherical aberrations (SAs), coma, and total HOAs significantly increased postoperatively in the 2 groups ( P < 0.05). The FS-LASIK group had greater changes in Q value and SA postoperatively than the SMI-LIKE group ( P < 0.01).

CONCLUSIONS

SMI-LIKE had similar safety and efficacy to FS-LASIK in the correction of moderate to high hyperopia. However, SMI-LIKE may equip better visual quality postoperatively for its lower Q value and SA changes than FS-LASIK.

Visual outcomes and corneal densitometry after allogenic and autologous lenticule intrastromal keratoplasty for the correction of moderate-to-high hyperopia

AIM

This study aimed to evaluate the visual outcomes and corneal densitometry (CD) after allogenic lenticule intrastromal keratoplasty (AL-LIKE) and autologous lenticule intrastromal keratoplasty (AU-LIKE) for the correction of moderate-to-high hyperopia.

METHODS

Ten subjects (14 eyes) underwent AL-LIKE and eight (8 eyes) underwent AU-LIKE. Patients were examined preoperatively and 1 day, 1 month, and 6 months postoperatively. The visual outcomes and CD for both surgical methods were evaluated.

RESULTS

No postoperative complications were observed with either method. The efficacy index was 0.85±0.18 and 0.90±0.33 in the AL-LIKE and AU-LIKE groups, respectively. The safety indices were 1.07±0.21 and 1.25±0.37 in the AL-LIKE and AU-LIKE groups, respectively. The CD values of the anterior, central, and posterior layers in the AL-LIKE group increased significantly at 1 day postoperatively (all P < 0.05). The CD values of the anterior and central layers remained significantly higher than the preoperative values at 6 months postoperatively (all P < 0.05). The CD values of the anterior layer in the AU-LIKE group increased significantly 1 day postoperatively (all P < 0.05) and decreased to preoperative values (all P > 0.05) 1 month postoperatively.

CONCLUSION

Both AL-LIKE and AU-LIKE exhibit good efficacy and safety in correcting hyperopia. However, AU-LIKE may have a smaller affected area and faster recovery time than those associated with AU-LIKE related to changes in corneal transparency.

Cornea plana in a family from Pakistan: Case series and literature review on the principles of management

Cornea plana (CP) is a rare ocular condition existing in two distinct clinical and hereditary forms: a milder, autosomal dominant type I and a more severe, autosomal recessive type II. The condition is more commonly found in Finnish, Saudi, and Czech families. We report three brothers from a consanguineous marriage that presented with complaints of decreased vision of varying degrees. All three of them have blue, thick, and hazy corneas with shallow anterior chamber depths. The additional features of CP type II were seen in the older two brothers including arcus lipoids, ill-demarcated limbus, and an accommodative squint. They were managed by the correction of refractive errors through spectacles and detailed counseling with follow-up visits to look for progressive complications. The management is mainly centered around optically or surgically correcting the developmental anomalies. This is complimented with proper genetic counseling and regular follow-up visits to look for and manage complications. There are, however, novel therapies that can be considered in these patients including corneal transplants or corneal stromal stem cellular therapies.

Twelve-month outcomes of single-step transepithelial photorefractive keratectomy for moderate hyperopia and hyperopic astigmatism

BACKGROUND

Conventional mechanical or alcohol-assisted photorefractive keratectomy (PRK) techniques for correction of hyperopia and hyperopic astigmatism were associated with inconsistent results. The aim of this study is to evaluate the 12-month visual and refractive outcomes of the relatively new single-step transepithelial photorefractive keratectomy (TE-PRK) for moderate hyperopia and hyperopic astigmatism.

METHODS

This is a prospective interventional study. Forty-eight eyes of 30 patients with moderate hyperopia or hyperopic astigmatism with a cycloplegic spherical equivalent refraction (SEQ) between 2.0 and 4.5 diopters (D) underwent single-step StreamLight® TE-PRK using EX500 excimer laser (Alcon Laboratories, USA). The main outcome measures were recorded at 6 and 12 months postoperatively including assessment of logarithm of the minimum angle resolution (logMAR) uncorrected and corrected distance visual acuity (UDVA, CDVA), cycloplegic refraction, corneal topographic changes as well as post-PRK peripheral haze grading.

RESULTS

The mean preoperative cycloplegic SEQ was significantly reduced from 3.21 ± 0.61 D to 0.35 ± 0.04 D and 0.41 ± 0.04 D at 6 and 12 months, respectively (P < 0.001). The mean preoperative UDVA significantly improved from 0.53 ± 0.02 logMAR to 0.07 ± 0.01 logMAR and 0.08 ± 0.01 logMAR at 6 and 12 months, respectively (P < 0.001) while the mean preoperative logMAR CDVA showed non-significant change over time throughout the study (P = 0.135). At the end of the study, 41 eyes (85.4%) achieved UDVA of 20/25 or better and no eye lost any lines of CDVA. Thirty-eight eyes (79.1%) had a postoperative cycloplegic cylinder of 0.5 D or less at 12 months. The mean preoperative mean keratometry showed significant increase at 6 and 12 months postoperatively (P < 0.001) while there was no significant change between the two postoperative visits denoting topographic stability (P = 0.058). The mean postoperative Q value at 6 and 12 months showed a significant prolate shift (P < 0.001). No haze was observed in 62.5% and 85.4% of the enrolled eyes at 6 and 12 months, respectively.

CONCLUSIONS

Single-step StreamLight® TE-PRK for moderate hyperopia and hyperopic astigmatism achieved acceptable visual and refractive outcomes.

TRIAL REGISTRATION

(Clinicaltrials.gov): NCT05261685, 2 March 2022, retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT05261685.

[Refractive surgery for hyperopia]

Hyperopia is a refractive error in which light is focused behind, instead of on, the retina. Clear vision can be obtained by accommodation, but in the long run, this results in eye strain. Hyperopia can be classified as low [≤2.00 diopters (D)], moderate (2.00-4.00 D) and high (>4.00 D). Detailed preoperative evaluation is necessary and essential to obtain good postoperative results. Various surgical techniques can be proposed to correct this ametropia. The main techniques used act either by modifying the corneal curvature with the Excimer laser or by implanting a phakic intraocular lens. The anatomical peculiarities of the hyperopic eye (small corneal diameter, short axial length, narrow anterior chamber or large kappa angle) make refractive surgery for hyperopia a considerable challenge. Large optical ablation zones now allow correction of high hyperopia by reducing the risks of optical aberrations and regression. The patient must be informed and understand the postoperative course, which differs from that of surgery for myopia.

Phakic intraocular lens implantation for the correction of hyperopia

The prevalence of myopia is much higher than hyperopia. Hence, there are relatively few studies investigating phakic intraocular lens (pIOL) implantation for the correction of hyperopia. This review aimed to summarize the available relevant literature on the efficacy and safety of pIOL implantation for the correction of hyperopia and hyperopic astigmatism. At present, two types of pIOLs are used to correct hyperopia and hyperopic astigmatism: anterior chamber iris-fixated pIOLs and posterior chamber implantable collamer lenses. Both have been found to be safe and effective. No serious events (eg, retinal or choroidal detachment, endophthalmitis) were reported in the reviewed articles. Implantation of pIOLs might be the optimal refractive surgery for the correction of high hyperopia.

Efficacy and safety of transepithelial photorefractive keratectomy

Transepithelial photorefractive keratectomy (PRK) was introduced to prevent complications from conventional PRK and femtosecond laser-assisted laser in situ keratomileusis (LASIK). In the 2-step platform, phototherapeutic keratectomy is followed by PRK. It did not show notable safety or efficacy superiorities over conventional PRK. In the conventional single-step transepithelial PRK, ablation of epithelium and stroma occurs in a single continuous session by an Amaris laser. It showed better comparative safety results. Reverse single-step transepithelial PRK and the platform using smart-pulse technology were recent improvements in the single-step Amaris laser. They provide a smoother postablative stromal bed counter. In the refined single-step platform, a modified nomogram is used for determination of ablation parameters, along with modifications in postablative measures. It yielded better comparative results in hyperopia. Controlled trials comparing reverse, smart-pulse technology-equipped, or refined platforms of single-step transepithelial PRK with other modern laser-assisted methods could provide more robust evidence on the topic. Some key elements with significant roles in post-transepithelial PRK outcomes are discussed.

Transepithelial Photorefractive Keratectomy for Hyperopia: A 12-Month Bicentral Study

PURPOSE

To investigate the safety, efficacy, and stability of transepithelial photorefractive keratectomy (PRK) for hyperopia.

METHODS

This interventional case series study at two sites included 55 eyes (31 patients) with hyperopia (0.50 to 6.00 diopters [D]), with or without astigmatism (0.00 to -3.00 D), that underwent one-step transepithelial PRK with a Amaris 500-Hz excimer laser (SCHWIND eye-tech-solutions, Kleinostheim, Germany). A 12-month follow-up was conducted. Preoperative and successive postoperative visual acuity, manifest refraction, haze, and other complication data were analyzed.

RESULTS

The preoperative mean spherical equivalent of 2.56 ± 1.90 D improved to emmetropia (-0.08 ± 0.14 D) by 6 months, with subsequent slight mean regression of 0.024 D (range: -0.75 to 0.50) until month 12. Of the treated eyes, 75% and 76.2% were within the target refraction of ±0.50 D at 6 and 12 months postoperatively, respectively. The final mean cylindric refraction was comparable to the preoperative value (-0.94 ± 0.12 to -0.71 ± 0.12 D, P = .17); however, it was induced in 23% of eyes. The preoperative mean uncorrected distance visual acuity logMAR of 0.54 ± 0.05 significantly improved to 0.15 ± 0.03 by month 12 (P < .0001), and 64.2% of the treated eyes gained an uncorrected distance visual acuity of 20/25 or better. Ten eyes (23.8%) lost one line of preoperative corrected distance visual acuity (CDVA). No eye lost two or more lines of preoperative CDVA. Four eyes with a 3+ degree of haze were observed by the final visit. No other notable complications occurred. The low hyperopic eyes exhibited better overall results compared to the moderate hyperopic group.

CONCLUSIONS

One-step transepithelial PRK with the Amaris 500-Hz excimer laser provided reasonable outcomes for the correction of hyperopia with or without mild to moderate astigmatism.

Comparision of Optical Low Coherence Reflectometry Versus Ultrasonic Biometry in High Hypermetropia

PURPOSE

To compare anterior chamber depth (ACD), axial length (AL), and lens thickness (LT) measurements obtained by the Lenstar LS 900 (Haag-Streit AG) optical low-coherence reflectometry with those obtained by the A-scan contact ultrasound among patients with moderate and high hypermetropia.

METHODS

Fifty-two eyes of 52 patients with moderate and high hypermetropia (spherical equivalent of +4 D or more) were examined in this study measurements of ACD, AL, and LT obtained by Lenstar were compared with those obtained by applanation A-scan ultrasound. All measurements were obtained by two independent examiners. The interdevice agreements were evaluated with Bland-Altman analyses.

RESULTS

The mean age of the patients was 54.78±12.77 years (range 18-74 years). The mean spherical equivalent refractive power was +5.16±1.12 D (+4.0 to +8.75). The mean values of ACD, AL, and LT with A-scan were 3.05±0.34, 21.55±0.75, and 4.33±0.49 mm, respectively, whereas these values were 2.99±0.45, 21.58±0.78, and 4.20±0.44 mm, respectively, with Lenstar. There was statistically significant difference of LT between the two methods (P=0.02). The mean differences (lower/upper limit of agreement) of the ACD, AL, and LT values for A-scan ultrasound and Lenstar were -0.06 (-0.594/0.474), 0.04 (-0.380/0.459), and -0.12 (-0.739/0.502), respectively.

CONCLUSION

Among patients with moderate and high hypermetropia, the biometric measurements of ACD, AL, and LT by ultrasound and optical biometry were determined to be correlated and there was a high degree of agreement between contact A-scan ultrasonic biometry and Lenstar.

Wound healing profiles of hyperopic-small incision lenticule extraction (SMILE)

Refractive surgical treatment of hyperopia still remains a challenge for refractive surgeons. A new nomogram of small incision lenticule extraction (SMILE) procedure has recently been developed for the treatment of hyperopia. In the present study, we aimed to evaluate the wound healing and inflammatory responses of this new nomogram (hyperopic-SMILE), and compared them to those of hyperopic-laser-assisted in situ keratomileusis (LASIK), using a rabbit model. A total of 26 rabbits were used, and slit lamp biomicroscopy, autorefractor/keratometer, intraocular pressure measurement, anterior segment optical coherence tomography, corneal topography, and in vivo confocal microscopy examinations were performed during the study period of 4 weeks. The corneas were then harvested and subject to immunofluorescence of markers for inflammation (CD11b), wound healing (fibronectin) and keratocyte response (HSP47). The lenticule ultrastructual changes were also analyzed by transmission electron microscopy. Out results showed that hyperopic-SMILE effectively steepened the cornea. Compared to hyperopic-LASIK, hyperopic-SMILE had less postoperative wound healing response and stromal interface reaction, especially in higher refractive correction. However, compared to myopic-SMILE, hyperopic-SMILE resulted in more central deranged collagen fibrils. These results provide more perspective into this new treatment option for hyperopia, and evidence for future laser nomogram modification.

Refraktive Langzeitergebnisse nach Huckepackimplantation

BACKGROUND

Piggyback lens implantation is an alternative to exchange of the original intraocular lens (IOL) to treat high anisometropia in pseudophakic eyes. We present our results.

PATIENTS AND METHOD

A second IOL (piggyback) was implanted in 27 patients from 2000 to 2006. Nineteen patients were clinically investigated late postoperatively, and data for the other eight patients were evaluated from the patients' files.

RESULTS

The patients were 65+/-9 years old. Follow-up time was 38+/-25 months. The mean preoperative spherical equivalent (SE) in the myopic eyes was -7.86+/-3.82 D and in the hyperopic eyes was 1.64+/-0.74 D. After surgery, the mean SE in the myopic eyes was -1.77+/-1.82 D and in the hyperopic eyes was -0.09+/-0.51 D. Postoperative anisometropia was reduced from 4.64+/-3.3 D. to 0.9+/-0.82 D.

CONCLUSION

Piggyback lens implantation is a safe and effective surgical procedure and is less traumatic than exchange of the original IOL.

Surgical Correction of Hyperopia

Surgical attempts to correct hyperopia have yielded varying results over the last 130 years. These techniques include the reshaping of the cornea through incisions, burns, or lamellar cuts with removal of peripheral tissue; the addition of central inlays; laser ablations; and the replacement of the crystalline lens. By examining the success of each surgical technique, the refractive surgeon may be able to make an informed decision on its indications and limitations, based on the specific patient's characteristics. Reporting the outcomes and complications of hyperopic surgery will help refine our approach to the management of an increasingly hyperopic and presbyopic population.