Outcome of complete intrastromal ring implantation using femtosecond laser in pellucid marginal degeneration

Outcomes of a Single-Segment Intrastromal Corneal Ring in Early Keratoconus and Early Pellucid Marginal Degeneration

PURPOSE

To determine the effect of a single-segment intrastromal corneal ring segment (ICRS; Intacs SK) on early keratoconus (KCN) and pellucid marginal degeneration (PMD).

METHODS

It is a prospective interventional study. One hundred twenty-four eyes (99 patients) with KCN and 36 eyes (26 patients) with PMD at early stage (the maximum keratometric reading less than 55 diopters) were included to ICRS implantation using femtosecond laser at a tertiary university-based hospital and a private outpatient center. The uncorrected distance and spectacle-corrected visual acuity (UDVA and SCDVA), manifest spherical and cylindrical refractions, and keratometry indices were measured preoperatively and postoperatively, 1 week, 2 and 6 months.

RESULTS

One week after surgery, significant improvements were observed in UDVA, SCDVA, cylinder and keratometry readings of both KCN and PMD groups (all P < 0.05) with no significant changes afterward. No significant change occurred in the sphere refraction of PMD group (P = 0.10) in contrast to KCN group (P < 0.001). Corneal irregularity of KCN group in central 3 and 5 mm zones increased at 1 week (both P < 0.001) and then started to decrease up to 6 months. However, the corneal irregularity of PMD group had significant reduction only at 1 week in 5-mm zone (P = 0.02) and 2 months in 3-mm zone (P = 0.01) postoperatively. The final efficacy indexes were 1.44 ± 0.71 and 0.87 ± 0.40 in KCN and PMD groups, respectively.

CONCLUSION

Visual acuity, refractive errors and keratometry values have been improved after one-segment Intacs SK implantation in early KCN and PMD patients.

Changes in the Optical Corneal Densitometry, Visual Acuity, and Refractive Error after the Annular Intracorneal Inlay Implantation

Purpose:

To investigate the changes in the optical corneal densitometry as an objective method in assessing the corneal light back-scattering before and 1 year after the annular intracorneal inlay (AICI) implantation into the keratoconic corneas.

Methods:

Changes in the optical corneal densitometry, visual acuity, refractive, and tomographical status were assessed before and 1 year after the AICI implantation into the corneas with different stages of keratoconus. Optical corneal densitometry was evaluated using the Pentacam-HR in 0–2, 2–6, 6–10, and 10–12 mm rings in the anterior 120 μ, central layers, posterior 60 μ and also the total value were measured for cornea in the Grey Scale Unit criterion.

Results:

Totally, 34 patients with keratoconus were studied; the uncorrected and best corrected visual acuity were increased after the surgery (0.98 ± 0.25 to 0.53 ± 0.30 logMAR, P < 0.001 and 0.26 ± 0.18 to 0.19 ± 0.14, P = 0.007 logMAR, respectively); the spherical equivalent was decreased from −4.45 ± 2.25 to − 2.06 ± 2.01 D (P = 0.004). AICI implantation led to an increase in the amount of optical corneal densitometry in 0–2 mm central, 2–6 mm central, 6–10 mm central, total central, 2–6 mm posterior, and 2–6 mm total rings (all, P < 0.05); however, a decrease was observed in 0–2 mm anterior ring (P = 0.049). Results of statistical analysis showed that the total optical corneal densitometry, anterior total, and posterior total back-scattering did not change after the AICI implantation (all, P > 0.05).

Conclusions:

Our results revealed a significant improvement in the visual function, including refractive error and visual acuity following the AICI implantation. Changes in the optical corneal densitometry were different in distinct regions and layers however, the total amount did not change after the AICI implantation.

Simultaneous Implantation of Refractive Lenticule and Intracorneal Ring Segment in the Management of Pellucid Marginal Degeneration

PURPOSE

To describe a patient with pellucid macular degeneration suffering from visual deterioration due to high irregular astigmatism and intolerant to contact lenses, who underwent a new surgical procedure that combined intrastromal lamellar keratoplasty and a 359° intracorneal ring segment implantation, enabling both ametropia and corneal thinning correction.

METHODS

Case report.

RESULTS

Refractive lenticule obtained during a myopic small incision lenticule extraction procedure was used as the donor lamellar graft. The technique described allowed for partial cylinder reduction and reinforcement of the thinned cornea. Uncorrected distance visual acuity improved from 0.02 to 0.5 (decimal) and corrected distance visual acuity improved from 0.4 to 0.7 with a decrease of 4.50 diopters in corneal astigmatism.

CONCLUSIONS

Despite the lack of long-term observation, the new technique described in this case report was successful for this specific patient and therefore might be effective and safe in severe stages of disease. [J Refract Surg. 2019;35(9):606-609.].

Surgical management of peripheral corneal thinning disorders

The peripheral corneal thinning disorders are associated with degenerative, autoimmune, or infective causes. Corneal thinning can subsequently affect the visual acuity either by inducing severe astigmatism or by progressive involvement of the central cornea. In addition to this, the integrity of the eye is at risk. Medical management is necessary to address the underlying inflammatory or infectious causes; however, most of the cases require surgical intervention for tectonic support or for visual rehabilitation in patients with severe astigmatism. Preoperative investigations help in mapping the corneal curvature and thickness, thereby facilitating planning of treatment. Routine corneal transplantation techniques do not yield good results in peripheral corneal thinning disorders. Various surgical modifications have been described to manage these challenging cases. We review the available literature on causes and management of peripheral corneal thinning disorders.

Clinical outcomes after implantation of a new intrastromal corneal ring with 140-degree of arc in patients with corneal ectasia

AIM

To evaluate the clinical and tomographic outcomes after implantation of a new intrastromal corneal ring segment (ICRS) with 140-degrees of arc in eyes with corneal ectasia.

METHODS

We evaluated patients with corneal ectasia implanted with Ferrara 140° ICRS from April 2010 to February 2015. Outcome measures included preoperative and postoperative corrected distance visual acuity (CDVA), keratometry simulated (K) reading, tomographic astigmatism and asphericity. All patients were evaluated using the Pentacam Scheimpflug system.

RESULTS

The study evaluated 58 eyes. The mean follow-up was 16.81±10.8mo. The CDVA (logMAR) improved from 0.5±0.20 (20/60) to 0.3±0.21 (20/40) (P<0.01). The average K reduced from 49.87±7.01 to 47.34±4.90 D (P<0.01). The asphericity changed from -0.60±0.86 to -0.23±0.67 D (P<0.01). The mean preoperative tomographic astigmatism decreased from -8.0±3.45 to -4.53±2.52 D (P<0.01).

CONCLUSION

The new ICRS model with 140-degrees of arc effectively improve the visual acuity and reduce the high astigmatism usually found in patients with corneal ectasia.