Clinical, tomographic, and topometric outcomes of progressive thickness intracorneal ring segment implantations in duck-type keratoconus

Purpose: To evaluate the visual, refractive, tomographic, and topometric outcomes of progressive thickness intracorneal ring segment (PT-ICRS) implantation in duck-type keratoconus. Methods: This retrospective study included eyes with oval (duck-type) keratoconus treated with PT-ICRS implantation. After the femtosecond laser tunnel creation, one PT-ICRS (Keraring AS 5 with 160° arc length) was implanted along the ectatic, inferior half of the cornea. Data of uncorrected and corrected distance visual acuity (UDVA and CDVA), refraction, asphericity (Q value), and keratometry (K) were compared pre- and postoperatively. Additionally, changes in the topometric indices of corneal irregularity were also evaluated after PT-ICRS implantation. Results: Thirty-one eyes of 30 patients were included in the study with a mean follow-up time of 9.06 months (ranging between 6 and 18 months). UDVA improved from 0.85 ± 0.36 to 0.27 ± 0.14 logMAR (P = 0.001), and CDVA improved from 0.37 ± 0.22 to 0.13 ± 0.11 logMAR (P = 0.001). The mean spherical error decreased from ?3.66 ± 2.60 to ?1.60 ± 1.42 D (P = 0.001), and the mean cylindrical error decreased from ?4.91 ± 2.65 to ? 1.41 ± 1.31 D (P = 0.001). All topographic parameters measured from the anterior cornea demonstrated statistically significant improvements after PT-ICRS implantation (P = 0.001). K mean, K maximum, corneal astigmatism, and Q value showed a significant decrease. Besides the index of height asymmetry, all topometric indices were significantly reduced after PT-ICRS implantation. There were no loss of lines and no complications. Conclusion: PT-ICRS implantation in duck-type keratoconus is an effective and safe treatment. This intervention improves the visual acuity, refractive error, topographical, and topometric parameters significantly by decreasing both eccentricity and steepness of the cone.

Influência da espessura dos segmentos de anel corneano na correção do astigmatismo ceratométrico em pacientes com ceratocone / Influence of corneal ring segment thickness on correction of corneal astigmatism in patients with keratoconus

RESUMO Objetivo: Avaliar retrospectivamente a influência da espessura do anel intracorneano na redução do astigmatismo corneano em pacientes portadores de ceratocone. Métodos: De um banco de dados com 2.033 olhos submetidos à cirurgia de implante de anel corneano, foi selecionada uma amostra de 90 olhos com características semelhantes em relação à ceratometria e ao astigmatismo. Todos os olhos deste estudo receberam dois segmentos de comprimento de arco tradicional de aproximadamente 160°, com espessuras variadas: Grupo A recebeu dois segmentos de 150µm; Grupo B recebeu dois segmentos de 200µm, e Grupo C recebeu dois segmentos de 250µm. As variáveis analisadas foram ceratometria média e astigmatismo corneano pré e pós-operatório. Resultados: Nos olhos que receberam dois segmentos de anel de 150µm de espessura (Grupo A), houve redução média de 5,0D (10%) em relação à ceratometria média e redução média de 3,26D (57,69%) em relação ao astigmatismo corneano. Na amostra em que foram utilizados dois segmentos de 200µm (Grupo B), foi observada redução da ceratometria média de 7,0D (14,28%) e do astigmatismo corneano de 3,53D (63,6%). Já na amostra que recebeu dois segmentos de anel de 250µm de espessura (Grupo C), a redução média da ceratometria foi de 10D (20,4%) e de seu astigmatismo corneano de 2,09D (38,99%). Conclusão: Nos pacientes com ceratocone submetidos à cirurgia de anel corneano, o aumento da espessura dos segmentos implantados promove maior aplanamento da córnea, mas não o aumento em sua capacidade de reduzir o astigmatismo ceratométrico. Seria interessante a análise de uma amostra maior de pacientes, aliada a cálculos vetoriais de astigmatismo, para comprovar os achados deste estudo.

ABSTRACT Objective: To retrospectively evaluate the influence of intracorneal ring thickness on reduction of corneal astigmatism in patients with keratoconus. Methods: From a database of 2,033 eyes submitted to corneal ring implant surgery, a sample of 90 eyes with similar keratometry and astigmatism characteristics was selected. All eyes in this study received two segments of traditional arc length of approximately 160°, with varying thicknesses: Group A received two segments of 150 µm; Group B received two segments of 200 µm, and Group C received two segments of 250 µm. The variables analyzed were mean keratometry and corneal astigmatism before and after surgery. Results: In the eyes that received two 150-µm ring segments (Group A), there was a mean reduction of 5.0 D (10%) in relation to mean keratometry, and a mean reduction of 3.26 D (57.69%) in relation to corneal astigmatism. In the sample in which two 200-µm segments (Group B) were used, there was a mean reduction in keratometry of 7.0 D (14.28%) and in corneal astigmatism of 3.53 D (63.6%). In the sample receiving two 250-µm ring segments (Group C), the mean reduction in keratometry was 10 D (20.4%) and in corneal astigmatism was 2.09 D (38.99%). Conclusion: In keratoconus patients undergoing corneal ring surgery, increased thickness of the implanted segments promotes greater flattening of the cornea, but does not enhance their ability to reduce corneal astigmatism. It would be interesting to analyze a larger sample of patients, combined with vector calculations of astigmatism, to confirm the findings of this study.

Comparison of preoperative and postoperative intraocular lens power values in eyes with Keraring implantation / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To evaluate intraocular lens power (IOL) calculation and biometry before and 3mo after implantation of Keraring 355° intrastromal corneal ring segment (ICRS;Mediphacos, Belo Horizonte, Brazil) in keratoconic eyes.METHODS: In this cohort study, data of 19 keratoconus eyes of 18 patients which undergone ICRS implantations were gathered before and 3mo after surgery.Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), manifest refraction, IOL power calculation formulas, axial lenght (AL) and keratometry were analayzed.RESULTS: Mean age of participants was 29.58±0.6.UCVA improved from 0.84 (0.35) logMAR to 0.43 (0.31) logMAR significantly (P<0.001).BCVA and AL didn`t change significantly after 3mo.All Sphere, cylinder and spherical equivalent (SE) were improved significantly (P<0.001).On the other hand, keratometry 1 (K1) and keratometry 2 (K2) decreased significantly.It was a considerable change in SRK/Ⅱ (P<0.001), Hoffer Q (P<0.001) and Holladay Ⅰ(P<0.001) after 3-month`s follow-up.Among this formula SRK/II had the lowest change.CONCLUSION: In addition to improvement in visual, refractive, and keratometry outcomes after Keraring implantation, there was a significantly changes in IOL calculation formulas values.However, ICRS procedure doesn`t interfere considerably AL in eyes, but it seems reduced keratometric values lead to IOL power calculations more accurately and all formulas suggested same IOL power.

A Case of Fungal Keratitis after Intracorneal Ring Segment Implantation for Keratoconus

PURPOSE: To report a case of fungal keratitis 3 days after intracorneal ring segment (ICRS) implantation for keratoconus. CASE SUMMARY: A 65-year-old woman was referred to our clinic with refractory infectious keratitis in her left eye 3 days after ICRS insertion for keratoconus. Slit lamp examinations revealed infiltrates around the incision site with cellular reaction in the anterior chamber after the ICRS had been removed. Corneal scrapings were obtained for staining and cultures, and intensive topical antibiotics were administered. Initial microscopy and cultures were negative. Despite the use of intensive topical antibiotics, there was no improvement. Hyphae were isolated from additional corneal scrapings. The patient's symptoms and corneal findings improved following administration of topical amphotericin B and oral itraconazole. CONCLUSIONS: Infectious keratitis after ICRS implantation is an uncommon but sight-threatening complication. Fungal keratitis should also be considered if infectious keratitis after ICRS is unresponsive to antibiotics.

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.