Visual, keratometric and corneal biomechanical changes after intacs SK implantation for moderate to severe keratoconus

Abstract

Purpose:To report visual outcomes and corneal biomechanical changes after femtosecond-assisted Intacs SK implantation in keratoconic eyes.Methods:This prospective interventional case series is comprised of 32 keratoconic eyes of 25 patients with mean age of 23.8 ± 5.4 years. Uncorrected (UDVA) and corrected (CDVA) distance visual acuity, refraction, manifest refraction spherical equivalent (MRSE), keratometry, central corneal thickness (CCT), corneal hysteresis (CH) and corneal resistance factor (CRF) were measured preoperatively, and 1, 3 and 6 months postoperatively.Results:Mean UDVA improved from 0.81 ± 0.3 LogMAR preoperatively to 0.53 ± 0.2 LogMAR six months postoperatively (P < 0.001). At 6 months, MRSE was significantly reduced only in eyes with moderate KCN (mean change, +2.61 ± 0.54 diopter [D]; P< 0.001). A significant improvement in sphere (mean change, +1.92 ± 0.37 D; P< 0.001) and mean keratometry (mean change, -3.34 ± 0.47D; P< 0.001) were observed. CCT increased from 446.1 ± 38 μm preoperatively to 462.2 ± 50 μm at six months (P < .001). CRF decreased from 6.5 ± 1.6 mmHg to 5.9 ± 1.1 mmHg six months after surgery (P = 0.02). CDVA, refractive cylinder and CH did not change significantly (P = 0.48, 0.203 and 0.55, respectively). Linear regression analysis disclosed that a decrease in CCT and moderate KCN are associated with higher CRF (standardized B,-0.513 and 0.314;P= 0.004 and 0.024, respectively; Adjusted R square = 0.353).Conclusion:Visual, refractive and keratometric indices remarkably improved in a parallel fashion. CRF was inversely associated with CCT. Changes in CRF represent the trend of changes in corneal biomechanics and thickness during the early postoperative months.

Intracorneal Stromal Ring Can Affect the Biomechanics of Ectatic Cornea

“…Zare et al examined corneal biomechanical changes after Intacs implantation. Despite reductions in CH and CRF following Intacs implantation, the changes were not statistically significant, which is in line with the results of the present study [ 17 ]. Thus, considering CH and CRF changes, the results of the present study are similar overall with previous research findings, which suggests the relative biomechanical stability of the cornea, at least at the first six-month follow-up after ICRS implantation, regardless of ring type, in KCN patients.…”

“…This effect might be due to the special design of the ring and its depth of implantation, as also mentioned in another study [ 19 ]. The study by Zare indicated that, after Intacs implantation, the cornea thickness increased within the first month after surgery [ 17 ]. Then, at the six-month follow-up after surgery, the thickness declined to some extent, though it did not reach the initial value [ 17 ].…”

Recent drug therapies for corneal neovascularization

“…Triamcinolone acetonide [133][134][135][136][137][138][139] inflammatory cells, IL-6, VEGF downstream pathways can significantly inhibit inflammatory corneal hemangiogenesis, but not lymphangiogenesis in vivo in the irritated cornea. [43] The combination of pegaptanib sodium and PDT lead to a significantly better anti-CNV effect than pegaptanib monotherapy.…”

“…At the meantime, triamcinolone acetonide enhanced the CNV inhibitory effect of bevacizumab as an adjuvant. [138] Researches showed that triamcinolone acetonide had no ocular toxicities in the anterior chamber. However, it can result in significant high IOP at 2 and 4 weeks after topical injection of triamcinolone acetonide (10 mg) into the vitreous cavity.…”

Obesity and Density of the Crystalline Lens: Revisiting a Growing Dilemma

“…Recent advances in techniques have provided objective and precise optical densitometry of the crystalline lens. The Pentacam HR technology (Oculus, Wetzlar, Germany) gives an objective and reproducible lens optical density (LOD) profile using the Scheimpflug principle [16,17,18], providing an evenly focused representation of a section of the lens because the plane of film parallels the optical section through the lens [19,20]. LOD has been shown to be associated with diabetes [21], nutritional elements [22], smoking, and sun exposure [23], as established risk factors of ARC.…”