Current review and a simplified “five‑point management algorithm” for keratoconus.

Keratoconus is a slowly progressive, noninflammatory ectatic corneal disease characterized by changes in corneal collagen structure and organization. Though the etiology remains unknown, novel techniques are continuously emerging for the diagnosis and management of the disease. Demographical parameters are known to affect the rate of progression of the disease. Common methods of vision correction for keratoconus range from spectacles and rigid gas‑permeable contact lenses to other specialized lenses such as piggyback, Rose‑K or Boston scleral lenses. Corneal collagen cross‑linking is effective in stabilizing the progression of the disease. Intra‑corneal ring segments can improve vision by flattening the cornea in patients with mild to moderate keratoconus. Topography‑guided custom ablation treatment betters the quality of vision by correcting the refractive error and improving the contact lens fit. In advanced keratoconus with corneal scarring, lamellar or full thickness penetrating keratoplasty will be the treatment of choice. With such a wide spectrum of alternatives available, it is necessary to choose the best possible treatment option for each patient. Based on a brief review of the literature and our own studies we have designed a five‑point management algorithm for the treatment of keratoconus.

Clinical Results of Intacs(R) Ring Implantation in Keratoconus or Keratectasia

PURPOSE: To report the clinical results after the implantation of intrastromal corneal ring segments (Intacs(R)) for the correction of keratoconus or keratectasia. METHODS: This retrospective study was comprised of 16 eyes treated by insertion of intrastromal corneal ring and 30 eyes treated by penetrating keratoplasty (PKP) who were diagnosed with keratoconus or keratectasia. Visual acuity, refractive outcome, keratometric values were evaluated before and at 3 months, 6 months, and 12 months postoperatively. In addition, the implanted ring segment depth was measured by anterior segment optical coherence tomography and the results were compared based on the depth of the ring. RESULTS: Twelve months after treatment, best corrected visual acuity (BCVA) was log MAR 0.32 at the ring group and log MAR 0.20 at the PKP group. BCVA change was larger at the PKP group than the ring group. Postoperative keratometric value was smaller at the ring group than at the PKP group. 3 mm irregular astigmatism was larger at the ring group than at the PKP group. The shallowly implanted ring group had a larger effect than the deeply implanted ring group. CONCLUSIONS: Intrastromal corneal ring segment implantation appears to be effective in improving the visual acuity and refractive outcome, although it cannot substitute for PKP.

Decision making nomogram for intrastromal corneal ring segments in keratoconus.

Purpose: To create a nomogram for the insertion of intrastromal corneal ring segments (ICRS) (Intacs®) in eyes with keratoconus. Sett ing: Tertiary eye care center in South India. Materials and Methods: This prospective, non-randomized, interventional case series used a self-designed decision-making nomogram for the selection of ICRS in keratoconus patients based on the centration of the cone, mean refractive spherical equivalent (MRSE), and mean keratometry (Km) values. The 3, 6, and 12 months clinical outcomes were compared to historical controls. Primary endpoints were improvement in uncorrected and best-corrected vision and change in the keratometric values. Results: Group A comprised of 52 eyes of 50 patients that followed the nomogram, while Group B comprised of 25 eyes of 23 non-nomogram historical controls matched for baseline parameters.In Group A, the uncorrected distance visual acuity (UDVA) improved from 0.16 ± 0.15 to 0.25 ± 0.16 (P < 0.001), corrected distance visual acuity (CDVA) from 0.58 ± 0.2 to 0.69 ± 0.21 (P = 0.022), MRSE from -5.41 ± 4.94 to -1.71 ± 2.88 (P < 0.001), Km from 51.77 ± 5.45 to 48.63 ± 4.37 (P < 0.001), and astigmatism reduced from 5.86 ± 2.61 to 4.91 ± 2.72 diopters (P < 0.001).In Group B, improvement in the average MRSE was from -6.44 ± 5.32 to -3.26 ± 2.82 (P < 0.013) and in the average Km from 53.64 ± 5.32 to 50.31 ± 5.02 (P < 0.001). Other parameters did not improve signifi cantly.A statistically signifi cant diff erence was present in the percentage of patients achieving a good clinical outcome between the two groups (P < 0.001; Chi-square). Conclusion: The nomogram provides a means to choose the appropriate ICRS, hence improving the outcome in patients with keratoconus.

The Clinical Results of Intacs(R) Ring Implantation by Manual Tunnel Creation in Patients with Keratoconus

PURPOSE: To report the clinical results after the implantation of intrastromal corneal ring segments (Intacs(R)) by manual tunnel creation for the correction of keratoconus. METHODS: This retrospective case series was comprised of 10 eyes of 8 consecutive keratoconic patients. Visual acuity, refractive outcome, keratometric values, anterior chamber depth, central corneal thickness, and endothelial cell density were evaluated before and at 1 month, 3 months, and 6 months postoperatively. In addition, the implanted ring segment depth was measured by anterior segment optical coherence tomography at postoperative 6 months. Any postoperative complications were also recorded. RESULTS: Visual acuity was improved in 9 out of 10 eyes. Spherical equivalent and keratometric values were decreased in all eyes. There was no significant difference in central corneal thickness, but endothelial cell density and anterior chamber depth were slightly decreased. The depth of ring segments was almost constant at superior, middle, and inferior. There was a single case of descented implanted ring segments and 6 cases of stromal infiltration around ring segments, but visual acuity was unaffected. In addition, 1 case showed implanted ring exposure, thus the superior ring segment was removed at postoperative 4 months. CONCLUSIONS: Intrastromal corneal ring segment implantation (Intacs(R)) by manual tunnel creation appears to be effective in improving the visual acuity and stabilizing corneal refractive power in keratoconic patients.

Intracorneal Ring Segment Implantation for the Management of Keratoconus: Short-Term Safety and Efficacy

PURPOSE: To assess the safety and efficacy of intracorneal ring segment (Intacs ring) implantation in managing keratoconus. METHODS: This retrospective case series comprised of 11 keratoconic eyes (11 patients) had Intacs ring (Addition Technology, Inc, California, USA) implantation. The main outcome measures were best corrected visual acuity, refraction, keratometry, topography, and pachymetry. Patients were examined before Intacs ring implantation as well as one week, one, three, and six months postoperatively. RESULTS: The mean best corrected visual acuity improved from 0.60+/-0.33 logMAR preoperatively to 0.39+/-0.23 logMAR six months postoperatively (p>0.05) and the mean corneal thickness, from 432.82+/-41.17 micrometer preoperatively to 448.00+/-62.27 micrometer at six months (p>0.05). The mean cylinder improved from -5.36+/-2.70D preoperatively to -2.50+/-1.66D six months postoperatively (p<0.05) and the mean keratometry, from 47.99+/-2.38D to 42.83+/-1.72D at six months (p<0.05). In addition, the mean spherical equivalent improved from -6.64+/-3.49D preoperatively to -3.66+/-3.37D six months postoperatively (p<0.05). One eye had a risk of ring exposure, but the others had no significant complications. CONCLUSIONS: Intacs ring implantation appears to be effective in improving cylinder, spherical equivalent, and keratometry in patients with keratoconus.

Posterior elevation maps and mean power keratometric maps to evaluate keratoconus and guide Intacs implantation: a step towards improving Intacs nomogram

Introduction: Keratoconos is a cornea disorder that affects young people and is a contraindication for refractive surgery; it could be treated with contact lens, corneal transplantation or with intracorneal ring segments (Intacs) insertion. Purpose: To compare mean power keratometric maps and posterior elevation maps in delineating keratoconus characteristics and guide Intacs implantation. Methods: 23 eyes with keratoconus, 12 subjects, cone area, cone radii, cone peak area and coordinates were measured using both maps and were compared using t test. Statistical significance was defined as p<0.05. Correlations were assessed with PearsonÆs coefficient. Results: Mean cone area was 17.65 mm² ± 4.63 and 35.68 mm² ± 9.72 in posterior elevation map and mean power keratometric analysis respectively (p 0.00). Both posterior elevation and mean power keratometric maps finds a similar percentage split between centre cones (CC) and de-centered cones (DC) of 78:22. However, 9% cases were found not to match after case to case evaluation. Conclusion: Based on the cases that not matched the cone centration, we suggest a new way to define the cone centre using the mean power keratometric map. Therefore, it should be review the decisions to implant symmetric rings vs. asymmetric rings using posterior elevation map. A new parameter is discussed ½cone peak centration¼ in de-centered cones (DC).

Introducción: El queratocono es una enfermedad que afecta individuos jóvenes y es una contraindicación para realizar cirugía refractiva; se puede manejar con lentes de contacto, queratoplastia o anillos intraestromales (Intacs¼). Propósito: Comparar los mapas topograficos mean power keratometric y elevación posterior en la delineación de las características del queratocono y guiar el implante de Intacs. Métodos: Se evaluaron 23 ojos con queratocono en 12 sujetos. Se midió el area del cono, el radio del cono, el area del pico del cono y sus coordenadas, en ambos mapas y se compararon usando la prueba t. La diferencia estadística se definió como p<0.05. Se realizaron correlaciones con el coeficiente de Pearson. Resultados: La media del ßrea del cono fue de 17.65 mm² ± 4.63 y 35.68 mm² ± 9.72 en el analisis con el mapa de elevación posterior y el mean power keratometric respectivamente (p 0.00). En ambos mapas se encontró un porcentaje de distribución similar entre conos centrados (CC) y conos descentrados (DC) de 78:22. Sin embargo, en la evaluación caso a caso, en 9% de los casos no hubo concordancia. Conclusión: Soportados en los resultados de la no concordancia con respecto a la centración del cono, se sugiere una nueva manera de definir el centramiento del queratocono usando el mapa mean power keratometric¼ y por tanto la decisión de implantar Intacs¼ simétricos o asimétricos sobre el modo tradicional con elevación posterior. Se discute un nuevo parametro la centración del pico del cono en DC.