Implantation of Artisan Toric Phakic Intraocular Lenses for the Correction of Astigmatism and Spherical Errors in Patients With Keratoconus

The efficacy of 2 different phakic intraocular lens implant in keratoconus as an isolated procedure or combined with collagen crosslinking and intra-stromal corneal ring segments: a systematic review and meta-analysis

PURPOSE

To compare the efficacy of phakic intra-ocular lenses in isolation or in combination with corneal crosslinking (CXL) and/or intra-stromal corneal ring segments (ICRS) in keratoconus.

METHODS

Data extracted from the publications meeting the selection. The outcome parameters included mean pre- and post-operative uncorrected distance visual acuity, corrected distance visual acuity (CDVA), sphere and cylinder of refraction and complications. Available data analyzed with Cochrane Review Manager.

RESULTS

A total of 23 studies including 464 eyes were included. All the parameters showed significant improvement in all subgroups other than CDVA in ACPIOL + CXL subgroup and cylinder in PIOL + CXL subgroups. There was not a significant difference between PCPIOL and ACPIOL in the outcomes, exception was more improvement of CDVA in "ACPIOL only" than" PCPIOL only" subgroup.

CONCLUSION

Both PCPIOLs and ACPIOLs are comparably safe and efficient options in management of KCN and their efficacy significantly improves when combined with CXL/ICRS.

Cataract surgery in Keratoconus revisited - An update on preoperative and intraoperative considerations and postoperative outcomes

PURPOSE

This review aims to evaluate and simplify the recent literature on preoperative surgical planning, intraoperative considerations, postoperative surprises, and their management in patients with keratoconus undergoing cataract surgery.

METHODS

A review of the literature was done to analyze all the pertinent articles on Keratoconus and cataract surgery.

RESULTS

The surgical planning of cataracts in eyes with keratoconus needs a multifaceted approach. Preoperatively, techniques such as cross-linking or the use of intra-corneal rings help stabilize the progression. Unreliable biometric measurements are a significant problem in keratoconus patients, especially in an advanced stage of the disease. It is better to consider actual K readings if the K value is less than 55D but for a K value, more than 55D using standard K values will prevent postoperative refractive surprises. For calculation of K values, an elevation-based device like pentacam gives better repeatability in mild to moderate cases whereas for advanced keratoconus none of the keratometers is reliable. Recently, the Kane keratoconus formula performed better in all stages of disease whereas previous studies showed good results with SRK/T formula is a mild and moderate disease. Monofocal intraocular lenses are a better choice in these patients. Toric lenses can be used in mild and stable keratoconus. Intraoperatively, the use of a customized RGP lens can overcome the challenge of image distortion and loss of visual perspective. Despite taking necessary measures, postoperative refractive surprise can occur and can be managed with IOL exchange or Secondary IOLs.

CONCLUSION

There is a spectrum of challenges in managing cataracts in keratoconus which makes thorough preoperative planning important for good surgical outcomes. Despite the measures, there might be post-operative surprises and the patients need to be informed regarding the same.

Toric Implantable Phakic Contact Lens in the Correction of Stable Keratoconus after Corneal Collagen Crosslinking

Background:

The study aims to evaluate the safety profile and efficacy of toric Implantable Phakic Contact Lens (IPCL) in patients with stable keratoconus after corneal collagen crosslinking (CXL).

Methods:

A prospective interventional case series study involving 30 keratoconic eyes between 22 to 39 years of age implanted with toric IPCL 6 months after CXL. The refractive error, visual acuity, corneal endothelium, intraocular pressure (IOP), and adverse effects were observed for 12 months following the implantation.

Results:

The preoperative mean for the sphere was approximately -8.3±3.6, which improved postoperatively by -0.58±0.23 after 1 month, -0.48±0.19 after 3 months, -0.36±0.18 after 6 months, and -0.35±0.2 after 12 months respectively. About the cylinder, the preoperative mean for the cylinder was approximately -3.4±1.6, which improved postoperatively by -1.06±0.3 after 1 month, -0.76±0.19 after 3 months, -0.48±0.28 after 6 months and -0.53±0.12 after 12 months, respectively. The preoperative BCDVA was 0.34±0.13, which increased postoperatively to 0.18±0.11 after 12 months. The mean values for IOP were 14.5±1.5 mm Hg, 15.1±2.09 mm Hg, 13.8±2.2 mmHg, 13.3±1.7 mm Hg, 13.1±1.6 mm Hg at preoperative period, 1 month, 3 months, 6 months and 12 months postoperatively. The mean preoperative endothelial count was 2912.9±111.1 per square millimeter, 2854.7±113.2 cells per square millimeter after 6 months, and 2829.0±112.2 cells per square millimeter after 12 months.

Conclusions:

Toric IPCL is a safe approach for treating residual refractive errors, particularly astigmatism, after 6 months of CXL in patients with stable KCS.

[Stage-appropriate treatment of keratoconus]

Keratoconus (KC) is a progressive cone-shaped corneal protrusion that causes paracentral thinning at the apex of the cone and typically occurs asymmetrically on both sides. After a careful anamnesis and classification of the degree of severity a targeted treatment appropriate to the stage of the disease is available. If the visual acuity is no longer sufficient, rigid gas-permeable contact lenses (CL) are fitted by a specialist. Riboflavin UVA cross-linking (CXL) is recommended in cases of progression and visual acuity that is still useful for the patient. Intracorneal ring segments (ICRS) are indicated for CL intolerance in cases of reduced visual acuity and a clear central cornea. If the stage is more advanced, deep anterior lamellar keratoplasty (DALK) or penetrating keratoplasty (PKP) is recommended. A PKP is contraindicated in acute KC but deep stromal sutures for readaptation of the Descemet tear with gas filling of the anterior chamber can considerably shorten the course. Almost no other eye disease is nowadays as easily accessible for an early instrument-based diagnosis and stage-appropriate treatment as KC.

Current Trends in Modern Visual Intraocular Lens Enhancement Surgery in Stable Keratoconus: A Synopsis of Do's, Don'ts and Pitfalls

Keratoconus is a relatively common ectatic, non-inflammatory corneal disorder that involves gradual visual deterioration through progressive alteration of the shape of the cornea. The corneal thinning, irregular astigmatism and higher order aberrations that occur as the disease progresses pose major challenges in the visual rehabilitation of such patients. This paper summarizes the current literature regarding the results of visual enhancement procedures in patients with stable keratoconus treated with standalone anterior or posterior chamber phakic intraocular lens implantation and monofocal, toric or multifocal toric intraocular lens implantation following phacoemulsification for age-related cataract extraction or refractive lens exchange.

Three-year follow-up of posterior chamber toric phakic intraocular lens implantation for the correction of high myopic astigmatism in eyes with keratoconus

AIM

To assess the clinical outcomes following the use of toric implantable collamer lenses (toric ICL, STAAR Surgical) for the correction of high myopic astigmatism with keratoconus.

METHODS

This retrospective study evaluated 21 eyes of 11 patients with spherical equivalents of -9.70±2.33 D (mean±SD) and astigmatism of -3.21±1.56 D who underwent toric ICL implantation for keratoconus. Preoperatively, and at 1, 3 and 6 months and 1, 2 and 3 years postoperatively, we assessed the safety, efficacy, predictability, stability and adverse events of the surgery.

RESULTS

The logarithm of the minimum angle of resolution (logMAR) uncorrected distance visual acuity (UDVA) and the logMAR corrected distance visual acuity (CDVA) were -0.06±0.11 and -0.12±0.09, respectively, at 3 years postoperatively. At 3 years, 67% and 86% of the eyes were within ±0.5 and ±1.0 D, respectively, of the targeted correction. Manifest refraction changes of 0.04±0.33 D occurred from 1 month to 3 years postoperatively. No significant change in manifest refraction (analysis of variance, p=0.989) or keratometry (p=0.951), or vision-threatening complications occurred during the observation period.

CONCLUSIONS

Toric ICL implantation is beneficial according to measures of safety, efficacy, predictability and stability for the correction of refractive errors for keratoconus during a 3-year observation period. The disease did not progress even in the late-postoperative period, suggesting the viability of this procedure as a surgical option for the treatment of such eyes.

Implantable Collamer Lens for Correction of Refractive Errors in Patients with Keratoconus following Collagen Cross-Linking: One Year Follow-up

Objective

The purpose of this study is to assess the predictability, safety, efficacy and stability of correction of refractive errors in patients with keratoconus using Visian implantable collamer lens (ICL) following collagen cross-linking.

Materials and methods

This prospective, non-comparative study evaluated 20 eyes of 14 patients with keratoconus subjected to implantation of intraocular collamer lens at least 1 year following collagen cross-linking and stable refraction. Mean preoperative myopia was −8.43 ± 5.13 Diopters (D) (–3.5 to −20.0D and mean cylinder was −2.19 ± 1.28D (0.0 to −4.5D). The preoperative spherical equivalent (SE) was −9.52 ± 5.33D (–3.75 to −21.25D). During the 12 months follow-up, uncorrected visual acuity, best corrected visual acuity, refraction, intraocular pressure and vaulting are measured.

Results

At 12 months postoperatively, 90% of eye had refractive cylinder of <1.0D with (p = 0.003) and 20 (100%) eyes was within ±0.75D of sphere at 1 year (r2 = 0.99) and (p = 0.0085). The mean postoperative BCVA in decimal was 0.498 ± 0.232, while the mean preoperative BCVA was 0.484 ± 0.285. The safety index at 12 months was 1.02. The mean postoperative UCVA in decimal was 0.498 ± 0.232 and the mean preoperative BCVA is 0.484 ± 0.29 and the efficacy index at 12 months was 1.01.

Conclusion

Implantation of Visian Intraocular collamer lens is predictable, safe and effective way to correct refractive error in patients with keratoconus following collagen cross-linking.

How to cite this article

Shuber HS. Implantable Collamer Lens for Correction of Refractive Errors in Patients with Keratoconus following Collagen Cross-Linking: One Year Follow-up. Int J Kerat Ect Cor Dis 2014;3(1):29-35.

Anterior segment characteristics of keratoconus eyes in a sample of Asian population

PURPOSE

To assess changes in anterior segment parameters of keratoconus eyes at different stages of the disease in a sample of the Asian population.

METHODS

Files of 32 patients (48 eyes) diagnosed as clinical keratoconus were assessed and the following parameters noted: central corneal thickness (CCT), thinnest corneal thickness (TCT), location of thinnest pachymetry, anterior chamber depth (ACD) at the centre from posterior corneal surface, ACD at 1, 2 and 3mm inferior-paracentral, ACD at thinnest pachymetry, anterior chamber volume (ACV) and anterior chamber angle (ACA). For analysis, keratoconus eyes were classified into 3 subgroups according to mean keratometry readings (mild: K≤47.0D, moderate: 47.0<K<52.0D, and severe: K≥52.0D). Forty-five subjects (45 right eyes) were recruited as a control group. They underwent Pentacam tomographic evaluation. The same parameters were recorded for control subjects as in the keratoconus patients.

RESULTS

Each keratoconus subgroup comprised of 16 eyes. CCT, TCT, ACD at centre, ACD at 1, 2mm inferior-paracentral and ACD at thinnest pachymetry were statistically different between mild and severe keratoconus groups (P<0.05). There were also significant differences between normal with each of the moderate and severe keratoconus groups (P<0.05). Non-significant differences were found in ACV (P=0.84) and ACA (P=0.71) between all measured groups.

CONCLUSION

With the exception of ACV and ACA, parameters that include CCT, TCT, ACD at centre, thinnest pachymetry and 1, 2 mm inferior-paracentral were significantly altered with progression of keratoconus. These findings may be useful in monitoring and management of keratoconus patients.

Toric implantable collamer lens for high myopic astigmatism in keratoconic patients after six months

BACKGROUND

The aim was to evaluate the safety, efficacy, stability and predictability of posterior chamber collagen copolymer phakic intraocular lens (pIOL) implantation to correct myopia and myopic astigmatism associated with keratoconus.

METHODS

The unaided vision and visual acuity, refraction and adverse events were measured in 22 keratoconic eyes of 14 patients after using an implantable collamer lens (ICL) (STAAR Surgical Inc.) to correct refractive error. The outcome was evaluated over six months.

RESULTS

The mean pre-operative spherical equivalent (SE) and cylinder changed from -4.98 ± 2.63 DS and -2.77 ± 0.99 DC to -0.33 ± 0.51 DS and -1.23 ± 0.65 DC, respectively at the end of six months. Before the surgery the mean Snellen decimal visual acuity was 0.63 ± 0.20. The mean unaided vision and visual acuity changed to 0.76 ± 0.23 and 0.85 ± 0.21, respectively at the end of six months. The mean safety and efficacy indices were 1.40 ± 0.32 and 1.24 ± 0.34, respectively. No eye lost a line of visual acuity and 17 eyes (77.3 per cent) gained one or more lines. Fifteen eyes (68.2 per cent) were within 0.50 D and 20 (90.9 per cent) were within 1.00 D of the desired spherical equivalent refraction. There was a change in manifest refraction of 0.09 ± 0.21 (ranging from -0.25 to +0.75) from one week to six months after the surgery.

CONCLUSION

The clinical outcomes of the current study demonstrate the safety, efficacy and predictability of toric implantable collamer lens in the correction of myopia and myopic astigmatism associated with keratoconus. The patients' refractions achieved early stability and remained stable during the course of the study.

Collagen crosslinking and toric iris-claw phakic intraocular lens for myopic astigmatism in progressive mild to moderate keratoconus

PURPOSE

To report the long-term results of combined collagen crosslinking (CXL) and toric phakic intraocular lens (pIOL) implantation to correct myopic astigmatism in patients with progressive mild to moderate keratoconus.

SETTING

Instituto de Microcirugia Ocular, Barcelona, Spain.

DESIGN

Case series.

METHODS

From November 2006 to July 2009, CXL was performed in eyes with proven progressive keratoconus. Once refraction and topography stabilized, toric Artiflex/Artisan pIOL implantation was performed to correct residual myopic astigmatism. A complete ophthalmologic examination, including manifest refraction, uncorrected (UDVA) and corrected (CDVA) distance visual acuities, biomicroscopy, tonometry, fundoscopy, keratometry, corneal tomography, and central endothelial cell count (ECC), was performed before each procedure and postoperatively at 3 months and at yearly intervals up to 5 years. Main outcome measures were accuracy and stability of the spherical equivalent (SE) and cylinder, keratometry, UDVA (efficacy), CDVA (safety), central ECC, and complications.

RESULTS

The median follow-up in the 9 patients (17 eyes) was 36.9 months ± 15.0 (SD). The median interval between CXL and pIOL implantation was 3.9 ± 0.7 months. Fourteen eyes (82%) were within ± 0.50 diopter (D) of the attempted SE correction and 13 eyes (76%) were within ± 1.00 D of the attempted cylinder correction. The mean difference in simulated keratometry between preoperatively and the last follow-up was 0.17 ± 0.45 D (range -0.55 to 1.45 D). The postoperative UDVA was 20/40 or better in 16 eyes (94%). No eye lost lines of CDVA. No significant decrease in central ECC occurred (P>.05).

CONCLUSION

Combined CXL and toric iris-claw pIOL implantation effectively and safely corrected myopic astigmatism in progressive mild to moderate keratoconus.

FINANCIAL DISCLOSURE

Dr. Güell is a consultant to Ophtec. No other author has a financial or proprietary interest in any material or methods mentioned.

Artisan iris-supported phakic IOL implantation in patients with keratoconus: a review of 16 eyes

PURPOSE

To evaluate the clinical outcomes of Artisan phakic intraocular lens (PIOL; Ophtec BV) implantation in patients with stable keratoconus.

METHODS

In a prospective, nonrandomized case series, 14 Artisan PIOLs and 2 toric Artisan PIOLs were implanted in 13 patients (16 eyes) with stable keratoconus who had contact lens intolerance. Pre- and postoperative data were collected.

RESULTS

Mean follow-up was 14.2 ± 7.8 months. Preoperative uncorrected distance visual acuity (UDVA) was counting fingers in all patients. Mean final logMAR (Snellen equivalent) UDVA and corrected distance visual acuity (CDVA) were 0.15(20/28) ± 0.13 and 0.11(20/26) ± 0.10, respectively. The improvements in UDVA and CDVA were statistically significant (P<.0001 and P<.002, respectively). All patients achieved a final UDVA of 20/40 or better, and 84.6% had a final CDVA of 20/32 or better. No postoperative complications occurred except for two cases of sterile uveitis.

CONCLUSIONS

Implantation of the Artisan PIOL is effective in improving visual acuity in patients with stable keratoconus. Long-term safety remains to be established as no postoperative endothelial cell counts were performed.

Artiflex phakic intraocular lens implantation after corneal collagen cross-linking in keratoconic eyes

PURPOSE

To evaluate the safety, efficacy, and stability of the Artiflex (Ophtec BV) foldable anterior iris-claw phakic intraocular lens (PIOL) following corneal collagen cross-linking (CXL) in select cases of progressive keratoconus.

METHODS

This prospective, comparative study, conducted between March 2007 and June 2008, involved 11 eyes with progressive keratoconus. Inclusion criteria were progressive keratoconus (Amsler-Krumeich classification grades I and II) with no corneal opacities, corneal thickness >450 μm, endothelial cell count >2500 cells/mm(2), anterior chamber depth >3.2 mm, spherical equivalent refraction >4.50 diopters (D) (with a cylinder component <2.00 D), and no other treatment for keratoconus other than contact lens. Each patient underwent CXL in the keratoconic eye with implantation of the Artiflex IOL 6 months thereafter. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and refraction and topographic profiles were examined at 1, 6, and 12 months after the CXL procedure.

RESULTS

All eyes achieved UDVA of 0.3 logMAR or better. Final spherical and cylindrical error ranged from 0 to -1.50 D and 0 to -1.75 D, respectively. No eyes lost lines of preoperative CDVA. Statistically significant reductions in mean maximum (2.14 D, P<.001) and minimum (1.17 D, P=.02) keratometry values were present 12 months after the CXL procedure. No complications were observed.

CONCLUSIONS

Combined CXL and Artiflex implantation was a safe and effective treatment in this subset of eyes with progressive keratoconus. Good results in terms of visual acuity, postoperative residual refractive error, and keratometry values were identified.

Clinical outcomes of posterior chamber toric phakic intraocular lens implantation for the correction of high myopic astigmatism in eyes with keratoconus: 6-month follow-up

BACKGROUND

To assess the early clinical outcomes of toric implantable collamer lenses (toric ICL™, STAAR Surgical) for the correction of high myopic astigmatism with keratoconus.

METHODS

This study evaluated 27 eyes of 14 patients with spherical equivalents of -10.11 ± 2.46 D (mean ± standard deviation) and astigmatism of -3.03 ± 1.58 D who underwent toric ICL implantation for mild keratoconus. Before, and 1, 3 and 6 months after surgery, we assessed the safety, efficacy, predictability, stability, and adverse events of the surgery.

RESULTS

LogMAR uncorrected visual acuity (UCVA) and LogMAR best spectacle-corrected visual acuity (BSCVA) were -0.09 ± 0.16 and -0.15 ± 0.09 respectively, 6 months after surgery. The safety and efficacy indices were 1.12 ± 0.18 and 1.01 ± 0.25. At 6 months, 85% and 96% of the eyes were within ±0.5 and ±1.0 D respectively of the targeted correction. Manifest refraction changes of 0.00 ± 0.35 D occurred from 1 week to 6 months. No vision-threatening complications occurred during the observation period.

CONCLUSIONS

Toric ICL implantation was good in all measures of safety, efficacy, predictability, and stability for the correction of spherical and cylindrical errors in eyes with early keratoconus throughout the 6-month follow-up period, suggesting its viability as a surgical option for the treatment of such eyes.

Collagen copolymer toric posterior chamber phakic intraocular lens in eyes with keratoconus

PURPOSE

To assess the safety, efficacy, stability, and predictability of collagen copolymer toric phakic intraocular lens (pIOL) implantation to correct myopia and astigmatism in eyes with keratoconus.

SETTING

Fernández-Vega Ophthalmological Institute, Oviedo, Spain.

METHODS

This prospective study comprised keratoconic eyes that had implantation of a toric Intraocular Collamer Lens. Uncorrected (UDVA) and corrected (CDVA) distance visual acuities, refraction, and postoperative complications were evaluated 1, 3, 6, and 12 months postoperatively.

RESULTS

Preoperatively, the mean spherical equivalent in the 30 eyes (21 patients) was -5.38 diopters (D) +/- 3.26 (SD) (range -13.50 to -0.63 D) and the mean cylinder, -3.48 +/- 1.24 D (range -1.75 to -6.00 D). At 12 months, 86.7% of the eyes were within +/-0.50 D of the attempted refraction and all eyes were within +/-1.00 D. For the astigmatic components J0 and J45, 83.3% of eyes and 86.7% of eyes, respectively, were within +/-0.50 D. The mean Snellen UDVA was 0.81 +/- 0.20 and the mean CDVA, 0.83 +/- 0.18; CDVA was 20/40 or better in 29 eyes 96.7% of eyes and 20/25 or better in 22 eyes (73.3%). No eyes lost more than 2 lines of CDVA; 29 eyes (96.7%) maintained or gained 1 or more lines. The efficacy index was 1.07 and the safety index, 1.16. There were no complications or adverse events.

CONCLUSIONS

The results confirm that toric ICL implantation is a predictable, effective procedure to correct ametropia in eyes with keratoconus. Predictability and stability were achieved early and remained fairly stable up to 12 months.

Collagen copolymer toric posterior chamber phakic intraocular lens in eyes with keratoconus

PURPOSE

To assess the safety, efficacy, stability, and predictability of collagen copolymer toric phakic intraocular lens (pIOL) implantation to correct myopia and astigmatism in eyes with keratoconus.

SETTING

Fernández-Vega Ophthalmological Institute, Oviedo, Spain.

METHODS

This prospective study comprised keratoconic eyes that had implantation of a toric Intraocular Collamer Lens. Uncorrected (UDVA) and corrected (CDVA) distance visual acuities, refraction, and postoperative complications were evaluated 1, 3, 6, and 12 months postoperatively.

RESULTS

Preoperatively, the mean spherical equivalent in the 30 eyes (21 patients) was -5.38 diopters (D) +/- 3.26 (SD) (range -13.50 to -0.63 D) and the mean cylinder, -3.48 +/- 1.24 D (range -1.75 to -6.00 D). At 12 months, 86.7% of the eyes were within +/-0.50 D of the attempted refraction and all eyes were within +/-1.00 D. For the astigmatic components J0 and J45, 83.3% of eyes and 86.7% of eyes, respectively, were within +/-0.50 D. The mean Snellen UDVA was 0.81 +/- 0.20 and the mean CDVA, 0.83 +/- 0.18; CDVA was 20/40 or better in 29 eyes 96.7% of eyes and 20/25 or better in 22 eyes (73.3%). No eyes lost more than 2 lines of CDVA; 29 eyes (96.7%) maintained or gained 1 or more lines. The efficacy index was 1.07 and the safety index, 1.16. There were no complications or adverse events.

CONCLUSIONS

The results confirm that toric ICL implantation is a predictable, effective procedure to correct ametropia in eyes with keratoconus. Predictability and stability were achieved early and remained fairly stable up to 12 months.

Combined Kerarings and Artisan/Artiflex IOLs in Keratectasia

PURPOSE:To evaluate the results of combined intracorneal ring (Keraring, Mediphacos Ltd) and anterior chamber, iris-fixated, phakic intraocular lens (pIOL) (Artisan and Artiflex, Ophtec BV) implantation in patients with ectatic corneal conditions and secondary high myopic and astigmatic refractive error. METHODS:Ten eyes of eight consecutive patients with different ectatic corneal diseases underwent sequential intracorneal Keraring and iris-fixated pIOL implantation. Two eyes with keratoconus, one eye with pellucid marginal degeneration, and one eye with iatrogenic corneal ectasia were implanted with the Artisan pIOL; six eyes with keratoconus were implanted with the Artiflex pIOL. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent (MRSE), topographic findings, and complications were recorded. RESULTS:Mean UDVA improved from 0.02+/-0.10 pre-operatively to 0.11+/-0.06 after Keraring implantation and to 0.54+/-0.18 after pIOL implantation (P<.001 for all). Mean CDVA improved from 0.18+/-0.12 preoperatively to 0.39+/-0.13 after Keraring implantation and to 0.66+/-0.18 after pIOL implantation (P<.001 for all). Mean MRSE reduced from -12.50+/-6.31 D preoperatively to +/-12.08+/-5.17 D after Keraring implantation (P=.10) and to -0.10+/-0.84 D after pIOL implantation (P<.001). No intra- or postoperative complications were observed. CONCLUSIONS:Sequential intracorneal Keraring segments and Artisan/Artiflex pIOL implantation resulted in visual and refractive improvements in patients with different corneal ectatic conditions with high myopic refractive errors.

Myopic phakic STAAR collamer posterior chamber intraocular lenses for keratoconus

PURPOSE

To evaluate the efficacy, predictability, and safety of myopic phakic posterior chamber Implantable Collamer Lens (ICL) to correct myopia associated with keratoconus.

METHODS

In a prospective, noncomparative, interventional case series, outcomes in 25 consecutive keratoconus eyes of 16 patients, myopia from -3.00 to -18.00 diopters (D) and astigmatism from -0.50 to -3.00 D, were analyzed 12 months after implantation of myopic ICLs (STAAR Surgical). All eyes showed best spectacle-corrected visual acuity (BSCVA) > or =20/50, central keratometric values < or =52.00 D, and refractive cylinder < or =3.00 D. Myopic ICL implantation was performed through a corneal incision in the steepest meridian.

RESULTS

The mean uncorrected visual acuity and BSCVA after ICL implantation were 0.17+/-0.19 and 0.12+/-0.12 logMAR, respectively. The efficacy index was 0.98. No eyes lost 2 or more lines of visual acuity, 2 eyes lost 1 line, 18 eyes did not change after surgery, and 5 eyes gained 1 or more lines. The safety index was 1.05. Best spectacle-corrected visual acuity after ICL implantation was statistically significantly better than preoperative BSCVA (P=.0021). Spherical equivalent refraction was within +/-1.00 D of the desired refraction in all cases and 84% of cases were within +/-0.50 D. Mean postoperative spherical equivalent refraction was 0.32+/-0.55 D at 12 months.

CONCLUSIONS

Myopic ICL implantation was a safe, effective, and predictable procedure for the correction of myopia associated with keratoconus.

Phakic toric Implantable Collamer Lens implantation for the correction of high myopic astigmatism in eyes with keratoconus

PURPOSE

To present two patients in whom phakic toric Implantable Collamer Lenses (toric ICL, STAAR Surgical) have been effective for the correction of high myopic astigmatism with stable keratoconus.

METHODS

Both patients had a history of contact lens intolerance, and refraction and corneal topography were stable for 3 to 4 years. Preoperatively, the manifest refraction was -10.00 -6.00 x 100 in case 1 and -8.00 -2.75 x 100 in case 2.

RESULTS

Postoperatively, the manifest refraction was +0.50 -1.00 x 90 in case 1 and -0.25 -1.25 x 100 in case 2. Uncorrected visual acuity and best spectacle-corrected visual acuity were markedly improved after implantation in both patients. No progressive sign of keratoconus was seen during 1-year follow-up.

CONCLUSIONS

Phakic toric ICL implantation may be an alternative for the correction of high myopic astigmatism in eyes with stable keratoconus.

Evaluation of anterior segment parameters in keratoconic eyes measured with the Pentacam system

PURPOSE

To evaluate the alteration in anterior chamber parameters with the progression of keratoconus using a rotating Scheimpflug camera.

SETTING

Inonu University, Turgut Ozal Medical Center, Ophthalmology Department, Malatya, Turkey.

METHODS

Two hundred sixteen eyes of 123 patients diagnosed with keratoconus and 224 eyes of 112 normal subjects were evaluated with a Pentacam Scheimpflug camera (Oculus Inc.). Keratoconic eyes were divided into 3 groups according to mean keratometer (K) readings: mild (K = less than 47.0 diopters [D]), moderate (K = 47.0 to 52.0 D), and severe (K = 52.0 D or higher). The following parameters were obtained: thinnest corneal thickness (TCT), anterior chamber depth (ACD), corneal volume (CV), anterior chamber angle (ACA), and anterior chamber volume (ACV).

RESULTS

One hundred twenty-nine eyes had mild keratoconus, 59 had moderate keratoconus, and 35 had severe keratoconus. There were no statistically significant differences between the keratoconus group and control group in age, sex, or eye distribution (P>.05). With the progression of the disease, TCT and ACD were statistically different between all groups (P<.05). There were statistically significant differences in ACA and CV measurements between the mild keratoconus and severe keratoconus groups (P<.05). Also, CV readings were significantly different between the control group and all keratoconus groups (P<.05), although there was no significant difference in ACA measurements (P>.05). Despite a progressive increase in the ACV with disease progression, the differences between groups were not statistically significant (P>.05) except between the severe keratoconus group and the control group (P<.05).

CONCLUSION

Anterior segment parameters of the eye showed significant alterations with the progression of keratoconus.

Intracorneal rings for keratoconus and keratectasia

Intrastromal corneal ring segments were designed to achieve refractive adjustment by flattening the cornea. Recently, they have been used to reshape keratoconic corneas to improve uncorrected visual acuity, best corrected visual acuity, and contact lens tolerance and to delay or prevent the need for keratoplasty. Intracorneal ring segments have several distinct and important advantages. New thicknesses and different ring sizes and the use of femtosecond lasers to dissect channels inside the cornea will likely improve the surgical outcomes. This article reviews the latest data published or presented at meetings on the correction of keratoconus and keratectasia by intracorneal ring segments.

Implantation of Artisan toric phakic intraocular lens following Intacs in a patient with keratoconus

We report a 24-year-old man with bilateral keratoconus in whom Intacs (Addition Technology, Inc.) were implanted in both eyes. The procedure was followed by Artisan toric phakic intraocular lens (Ophtec) implantation to correct the residual myopic and astigmatic refractive error.

Artisan iris-fixated toric phakic and aphakic intraocular lens implantation for the correction of astigmatic refractive error after radial keratotomy

We report 2 patients who had radial keratotomy (RK) to correct myopia. The first patient developed a postoperative hyperopic shift and cataract. Nine years post RK, she had intracapsular cataract extraction and implantation of an Artisan aphakic intraocular lens (IOL). Twenty years post RK, hyperopia and astigmatism progressed to +7.0 -5.75 x 100 with a best corrected visual acuity (BCVA) of 20/20. Due to contact lens intolerance, the Artisan aphakic IOL was exchanged for an Artisan toric aphakic IOL. Three months later, the BCVA was 20/20 with +1.0 -0.50 x 130. The second patient demonstrated residual myopic astigmatism 6 years after bilateral RK and had become contact-lens intolerant. An Artisan toric phakic IOL was implanted in both eyes. Four months later, the BCVA was 20/25 with a refraction of +0.25 -1.0 x 135 and 20/20 with a refraction of -1.0 x 40. Both patients were satisfied with the visual outcomes.

Use of Verisyse iris-supported phakic intraocular lens for myopia in keratoconic patients

We report 2 patients with stable keratoconus and high myopia who benefited from implantation of an iris-supported phakic intraocular lens (Verisyse, AMO) for correction of their refractive error. Both patients had a postoperative uncorrected visual acuity of 20/40. Endothelial cell density showed at most a 4% decrease, and no evidence of keratoconus progression was witnessed. The use of the Verisyse lens may be beneficial for certain keratoconic patients as an alternative step between rigid gas-permeable lenses and penetrating keratoplasty.

Post-laser in-situ keratomileusis ectasia: current understanding and future directions

PURPOSE OF REVIEW

The aim of this article is to review the causes, risk factors, management, and future research directions for corneal ectasia after laser in situ keratomileusis.

RECENT FINDINGS

Complex corneal biomechanical processes influence the integrity of the normal and postoperative cornea, and developing an understanding of these processes facilitates recognition of risk factors for ectasia after laser in-situ keratomileusis. Currently identified risk factors include keratoconus, high myopia, low residual stromal bed thickness from excessive ablation or thick flap creation, and defined topographic abnormalities such as forme fruste keratoconus and pellucid marginal corneal degeneration. Ectasia can also rarely occur in patients without currently identifiable risk factors, and future identification of at-risk patients may be facilitated by corneal interferometry and corneal hysteresis measurements. Utilization of intraoperative pachymetry measurements at the time of surgery and confocal microscopy prior to enhancement to measure residual stromal bed thickness should avoid unanticipated low residual stromal bed thickness. Management options for ectasia after laser in situ keratomileusis include intraocular pressure reduction, rigid gas permeable contact lenses, and intracorneal ring segments, in addition to corneal transplantation. In the future, collagen cross-linking may reduce corneal steepening and improve refractive error.

SUMMARY

When ectasia develops, early recognition and proper management are essential to prevent progression, to promote visual rehabilitation, and to reduce the need for corneal transplantation for these patients.

Refractive lens exchange in keratoconus

PURPOSE

To evaluate the visual results and complications of refractive lens exchange to correct myopia associated with early-stage keratoconus.

SETTING

Private practice, Siena, Italy.

METHODS

This prospective noncomparative interventional series comprised 34 consecutive eyes of 20 patients with stages I to II keratoconus. Mean patient age was 56.7 years +/- 10.4 (SD). Preoperative mean spherical equivalent (SE) was -11.0 +/- 4.65 diopters (D), (range -5.75 to -22). Ultrasound biometry was performed using videokeratographic central K-readings and the Holladay 2 formula. An intraoperative handheld autorefractor was used to check the power of implanted intraocular lenses.

RESULTS

Intraocular lens exchange due to inaccurate power occurred in 11 eyes (32%; 9 eyes intraoperative, 2 eyes postoperative). At 12 months, mean SE was -1.31 +/-1.08 D and mean defocus equivalent was 1.94 +/- 1.57 D. Twenty-two eyes (65%) were within +/-2 D of defocus equivalent, 16 eyes (47%) were within +/-1 D, and 3 eyes (9%) were within +/-0.5. Mean surgically induced astigmatism (vector analysis) was 0.54 +/- 0.43 D. Preoperative mean best spectacle-corrected visual acuity (BSCVA) was 0.55 +/- 0.20, and postoperative mean BSCVA was 0.76 +/- 0.23; the difference was statistically significant (P<.05; 95% confidence interval, 0.19 to 0.25). Postoperative mean uncorrected visual acuity was 0.48 +/- 0.25. The safety index was 1.38, and the efficacy index was 0.87. Complications were posterior vitreous detachment (9%) and dysphotopsia phenomena (15%). Corneal endothelial cell density at 12 months decreased by 6.3%.

CONCLUSION

Refractive lens exchange in keratoconic eyes predictably corrected myopia. However, ultrasound biometry was inaccurate in almost one third of eyes. Intraoperative autorefractometry is recommended to improve refractive outcome.