INTACS inserts for treating keratoconus: One-year results

doi:10.1016/S0161-6420(01)00646-7

Ophthalmology

Volume 108, Issue 8, August 2001, Pages 1409-1414

Presented in part at the American Academy of Ophthalmology annual meeting, Dallas, Texas, October 2000.

https://doi.org/10.1016/S0161-6420(01)00646-7 Get rights and content

Abstract

Objective

To evaluate the use of INTACS micro-thin prescription inserts (Kera Vision, Inc., Fremont, CA) for the treatment of keratoconus.

Design

Prospective, nonrandomized (self-controlled) comparative trial.

Participants/intervention

Ten patients from our prospective clinical study who had completed 12 months of follow-up were evaluated. All patients had keratoconus with clear central corneas and were contact lens intolerant. After reviewing corneal pachymetry and topography of individual patients, INTACS inserts of 0.45-mm thickness were placed in the inferior cornea to lift the cone and INTACS of 0.25-mm thickness were inserted superiorly to counterbalance and flatten the overall anterior corneal surface.

Main outcome measures

Differences between preoperative and postoperative uncorrected visual acuity, best spectacle-corrected visual acuity, manifest refraction, and keratometry values were statistically assessed. Changes in corneal ectasia were evaluated by reviewing corneotopographic maps.

Results

No intraoperative complications occurred in this series of patients. Spherical equivalent error and refractive astigmatism were reduced with INTACS inserts treatment. Postoperative month 12 uncorrected visual acuity (logarithm of the minimum angle of resolution [logMAR] mean, 0.35, standard deviation [SD], 0.16 [∼20/50, ∼2 lines]) was significantly better than preoperative (logMAR mean, 1.05; SD, 0.33 [∼20/200, ∼3 lines]; P ≤0.05). Average best spectacle-corrected visual acuity at postoperative month 12 was improved by approximately two lines compared with baseline (logMAR mean, 0.22; SD, 0.12 [∼20/32, ∼1 line]; logMAR mean, 0.38; SD, 0.13 [∼20/50, ∼1 line], respectively). Topographic corneal shape (size and height of the cone) was improved for all subjects after insert placement.

Conclusions

INTACS micro-thin prescription inserts seem to provide a viable method for treating clear corneal keratoconus for patients who are contact lens intolerant. The corneal steepening and astigmatism associated with keratoconus were reduced, and visual acuity was improved with treatment in almost all eyes.

Section snippets

Patients and methods

All patients included in this study were referred to our institution for PK to treat keratoconus. Enrolled patients had keratoconus with clear central cornea and were contact lens intolerant. Patients had best spectacle-corrected visual acuity of 20/100 or better in the treatment eye and corneal thickness of 400 μm or more at the location where INTACS inserts were to be placed. When both eyes of a patient were eligible for study enrollment, the eye with the worse visual acuity was included for

Results

The average age of the patients was 30.9 ± 6.1 years. No intraoperative complications occurred in this patient series; both inferior and superior intrastromal tunnels for placement of INTACS inserts were made without any technical problems. INTACS inserts were removed 2 months postoperatively from one patient eye currently enrolled in our prospective clinical series (n = 23) because of superficial placement. INTACS inserts were removed easily under topical anesthesia, after opening the original

Discussion

The objective of using INTACS inserts for treating keratoconus is not to eliminate the corneal disease but to decrease corneal abnormality associated with it and improve visual acuity in affected patients to satisfactory levels. An important potential benefit of treating keratoconus with INTACS inserts is to delay or eliminate the need for a corneal graft. Postoperative results of our series of patients demonstrated that spherical equivalent error and astigmatism were significantly reduced and

References (18)

J Colin et al.
Myopic photorefractive keratectomy in eyes with atypical inferior corneal steepening
J Cataract Refract Surg
(1996)
I Kremer et al.
Three year results of photoastigmatic refractive keratectomy for mild and atypical keratoconus
J Cataract Refract Surg
(1998)
H.E Kaufman et al.
Epikeratophakia for the treatment of keratoconus
Am J Ophthalmol
(1982)
J.H Krumeich et al.
Live-epikeratophakia for keratoconus
J Cataract Refract Surg
(1998)
D.J Schanzlin et al.
The intrastromal corneal ring segments. Phase II results for the correction of myopia
Ophthalmology
(1997)
T.E Burris et al.
Flattening of central corneal curvature with intrastromal corneal rings of increasing thicknessan eye-bank eye study
J Cataract Refractive Surg
(1993)
J.H Lass et al.
Clinical management of keratoconus. A multicenter analysis
Ophthalmology
(1990)
M.R Dana et al.
Contact lens failure in keratoconus management
Ophthalmology
(1992)
S.J Doyle et al.
PRK in patients with a keratoconic topography picture. The concept of a physiological “displaced apex syndrome.”
Br J Ophthalmol
(1996)

There are more references available in the full text version of this article.

Cited by (224)

Cataract surgery following refractive surgery: Principles to achieve optical success and patient satisfaction
2024, Survey of Ophthalmology
A growing number of patients with prior refractive surgery are now presenting for cataract surgery. Surgeons face a number of unique challenges in this patient population that tends to be highly motivated to retain or regain functional uncorrected acuity postoperatively. Primary challenges include recognition of the specific type of prior surgery, use of appropriate intraocular lens (IOL) power calculation formulas, matching IOL style with spherical aberration profile, the recognition of corneal imaging patterns that are and are not compatible with toric and/or presbyopia-correcting lens implantation, and surgical technique modifications, which are particularly relevant in eyes with prior radial keratotomy or phakic IOL implantation. Despite advancements in IOL power formulae, corneal imaging, and IOL options that have improved our ability to achieve targeted postoperative refractive outcomes, accuracy and predictability remain inferior to eyes that undergo cataract surgery without a history of corneal refractive surgery. Thus, preoperative evaluation of patients who will and will not be candidates for postoperative refractive surgical enhancements is also paramount. We provide an overview of the specific challenges in this population and offer evidence-based strategies and considerations for optimizing surgical outcomes.
CLEAR – Medical use of contact lenses
2021, Contact Lens and Anterior Eye
The medical use of contact lenses is a solution for many complex ocular conditions, including high refractive error, irregular astigmatism, primary and secondary corneal ectasia, disfiguring disease, and ocular surface disease. The development of highly oxygen permeable soft and rigid materials has extended the suitability of contact lenses for such applications. There is consistent evidence that bandage soft contact lenses, particularly silicone hydrogel lenses, improve epithelial healing and reduce pain in persistent epithelial defects, after trauma or surgery, and in corneal dystrophies. Drug delivery applications of contact lens hold promise for improving topical therapy. Modern scleral lens practice has achieved great success for both visual rehabilitation and therapeutic applications, including those requiring retention of a tear reservoir or protection from an adverse environment. This report offers a practical and relevant summary of the current evidence for the medical use of contact lenses for all eye care professionals including optometrists, ophthalmologists, opticians, and orthoptists. Topics covered include indications for use in both acute and chronic conditions, lens selection, patient selection, wear and care regimens, and recommended aftercare schedules. Prevention, presentation, and management of complications of medical use are reviewed.
Biomicroscopic Findings and Management of Anterior Stromal Necrosis After Long-term Implantation of Intacs
2020, American Journal of Ophthalmology
We sought to evaluate the visual, refractive, and biomicroscopic findings pre- and posttreatment of observed anterior stromal necrosis (ASN) after long-term Intacs intracorneal ring segment (ICRS) implantation.
Consecutive interventional case series.
All consecutive patients implanted with Intacs ICRS at a single center by 1 of the authors between October 2006 and October 2011 with a minimum follow-up time of 5 years were included. All Intacs were implanted using the Prolate system console and instrumentation from Addition Technology Inc (Chicago, Illinois, USA). The slit lamp, refractive, and visual findings and the management of those patients are described in detail. The primary outcome measures included the size of the epithelial defect overlying the Intacs body, the intended implantation depth measured by high-magnification slit lamp photography, and the management of the cases described in detail. The percentage of eyes with ASN out of those that reached the 5-year follow-up is reported.
One hundred twenty-seven eyes (84 patients) were implanted with 215 ICRSs during the study period, and 77.16% (98/127) eyes had a follow-up of ≥5 years, out of which 9 eyes (7 patients) had ASN corresponding to at least 9.18% (95% confidence interval 4.29%-16.72%). The mean ± standard deviation time between implantation and ASN diagnosis was 10.5 ± 1.3 years.
After 5 years of implantation, INTACS-treated eyes could present with an ASN over the ICRS body. Longer-term follow-up of patients implanted with INTACS is important to monitor if this complication keeps occurring over time.
Effects of a semi-scleral contact lens on refraction and higher order aberrations
2019, Contact Lens and Anterior Eye
To investigate effects of Rose K2 XL semi-scleral contact lenses (Menicon Co.) on visual acuity and higher-order aberrations in eyes with irregular corneas. Methods: One hundred and twelve eyes of 84 patients fitted with Rose K2 XL lenses were analysed. Participants were in 4 clinical groups: keratoconus, intra-corneal ring segments, radial keratotomy, and penetrating keratoplasty. Corrected distance visual acuity and ocular aberrations were determined before lens wear and 60 min into lens wear. The i-Trace aberrometer was used to determine aberrations at 4.5 mm pupil size.
There were 55, 22, 19 and 16 eyes in keratoconus, intra-corneal ring segments, radial keratotomy and penetrating keratoplasty groups, respectively. Before lens wear, eyes had poor corrected distance vision acuity (mean and standard deviation +0.55 ± 0.33 logMAR), high negative spherical equivalent refraction (−6.4 ± 3.7 D), high cylindrical errors (4.5 ± 2.2 D), large higher-order root-mean-squared (HO-RMS) aberration (1.5 ± 1.3 μm) and large higher-order aberration components. Cylinder was particular high for the penetrating keratoplasty group (mean 5.9 ± 2.5 D), root-mean-squared third-order coma was lowest for the radial keratotomy group (0.7 ± 1.0 μm), and fourth-order spherical aberration was highly negative for the intra-corneal ring segment group (co-efficient –0.4 ± 0.7 μm). With lens wear, the values changed considerably. Corrected distance visual acuity improved by 0.51 ± 0.31 logMAR, cylinder decreased by 3.6 ± 2.1 D, HO-RMS aberration reduced by 1.1 ± 1.2 μm, and higher-order aberration components decreased considerably. Magnitudes of group changes reflected the magnitudes before lens wear.
Rose K2 XL semi-scleral contact lenses were effective in improving vision and reducing ocular aberrations for eyes with irregular corneas.
Visual quality with corneo-scleral contact lenses after intracorneal ring segment (ICRS) implantation for keratoconus management
2019, Contact Lens and Anterior Eye
To evaluate the visual quality results when fitting a corneo-scleral contact lens (CScL) after intracorneal ring segment (ICRS) implantation for keratoconus management.
Twenty-seven eyes of 27 patients with keratoconus underwent ICRS implantation and had CScL fitted as their visual quality was unsatisfactory with their spectacles or contact lenses. Patients received a complete eye examination, refraction and visual acuity assessment, anterior eye biomicroscopy, ocular fundus examination, corneal topographic analysis, endothelial-cell count, and visual quality assessment using contrast sensitivity and aberrometry tests. A diagnostic trial set was used in the fitting process, and patients were assessed according to a standardised methodology, including subjective visual quality and comfort, and contact lens usage time. The follow-up period was one year.
After fitting CScL, log-MAR visual acuity values improved significantly in relation to the best spectacle-corrected vision (0.22 ± 0.17 vs 0.00 ± 0.12; p < 0.001). Total high-order aberrations decreased 33% (2.62 ± 1.31 vs 1.75 ± 1.81 μm; p < 0.009) and the spatial frequencies of contrast sensitivity all improved (all p < 0.05). Furthermore, 70.37% of patients reported high ratings of subjective visual quality (favourable and very favourable) and prolonged usage times (11.78 ± 3.93 h). After wearing CScL for one year, no adverse ocular effects or clinically relevant changes in corneal parameters, visual quality, comfort ratings or usage time were found.
This CScL appears to be an alternative reasonable option for keratoconic eyes with ICRS placement, providing an improvement in subjective visual quality.
Customized corneal allogenic intrastromal ring segments (CAIRS) for keratoconus with decentered asymmetric cone
2023, Indian Journal of Ophthalmology

View all citing articles on Scopus

¹: Debby Holmes-Higgin is an employee of KeraVision, Inc.

View full text

INTACS inserts for treating keratoconus: One-year results

Abstract

Objective

Design

Participants/intervention

Main outcome measures

Results

Conclusions

Section snippets

Patients and methods

Results

Discussion

J Cataract Refract Surg

J Cataract Refract Surg

Am J Ophthalmol

J Cataract Refract Surg

Ophthalmology

J Cataract Refractive Surg

Ophthalmology

Ophthalmology

PRK in patients with a keratoconic topography picture. The concept of a physiological “displaced apex syndrome.”

Br J Ophthalmol