Purpose: To compare the visual, refractive, and keratometric outcomes of single-segment conventional and severe keratoconus (SK) types of INTACS for correction of inferior keratoconus (KCN).Methods: A total number of 41 consecutive eyes of 23 patients with a diagnosis of inferior KCN underwent INTACS IMPLANTation. Eight eyes were excluded due to postoperative complications (4 eyes) and loss to follow‑up (4 eyes) and finally 33 eyes underwent statistical analysis. Two groups were created according to INTACS type insertion; conventional group (17 eyes) and SK groups (16 eyes). Intracorneal ring segments (ICRS) IMPLANTation was indicated in keratoconic patients with contact‑lens intolerance or reduced best spectacle-corrected visual acuity (BSCVA).Results: In the conventional group, mean uncorrected distance visual acuity (UCDVA) improved from 0.45±0.41 preoperatively to 0.69±0.39 six months after surgery representing a gain of 2 Snellen lines, and in the SK group mean UCDVA changed from 0.40±0.35 preoperatively to 0.58±0.48 equivalent to two Snellen lines improvement 6 months after operation (P=0.48). Mean preoperative BSCVA in the conventional group improved from 0.72±0.41 to 0.86±0.39 (2 lines improvement) postoperatively and in the SK group improved from 0.71±0.69 to 0.75±0.45 (0.50 line improvement) (P=0.29). Mean preoperative spherical equivalent (SE) decreased from -4.86 ± 2.26 D to-3.57±2.21 D (conventional group) and from -4.20±1.82 D to −3.60±1.89 D (P=0.34), mean astigmatism (AST) decreased from -5.20±2.07 D and -4.50±2.26 D to -4.02 ± 2.57 D and - 3.18±2.14 D in the conventional and SK groups, respectively (P=0.68). Finally, mean K min decreased from 47.11±2.51 D to 45.40±3.30 D in the conventional group and from 45.05±2.59 D to 44±3.88 D in the SK group (P=0.63) and mean K max was decreased from 52.82±3.23 D to 50.52±3.57 D and from 49.72±3.17 D to 48.55±4.50 D, respectively (P=0.48).Conclusion: Single‑segment IMPLANTation of conventional and SK INTACS improved UCDVA and BSCVA, decreased corneal AST and keratometry in both groups with comparable outcomes.

The objective of the present study was to compare single segment and double segment INTACS rings in the treatment of post-LASIK ectasia. In this interventional study, 26 eyes with post-LASIK ectasia were assessed. Ectasia was defined as progressive myopia regardless of astigmatism, along with topographic evidence of inferior steepening of the cornea after LASIK. We excluded those with a history of intraocular surgery, certain eye conditions and immune disorders, as well as monocular, pregnant and lactating patients. A total of 11 eyes had double ring and 15 eyes had single ring IMPLANTation. Visual and refractive outcomes were compared with preoperative values based on the number of IMPLANTed INTACS rings. Pre and postoperative spherical equivalent were -3.92 and -2.29 diopter (P=0.007). The spherical equivalent decreased by 1±3.2 diopter in the single-segment group and 2.56±1.58 diopter in the double-segment group (P=0.165). Mean preoperative astigmatism was 2.38±1.93 diopter which decreased to 2.14±1.1 diopter after surgery (P=0.508), 0.87±1.98 diopter decrease in the single-segment group and 0.67±1.2 diopter increase in the double-segment group (P=0.025). Nineteen patients (75%) gained one or two lines, and only three, who were all in the double-segment group, lost one or two lines of best corrected visual acuity. The spherical equivalent and vision significantly decreased in all patients. In these post-LASIK ectasia patients, the spherical equivalent was corrected better with two segments compared to single segment IMPLANTation; nonetheless, the level of astigmatism in the single-segment group was significantly better than that in the double-segment group.

Purpose: To present the clinical features, biomechanical properties and management of a patient who developed unilateral corneal ectasia after photorefractive keratectomy (PRK).Case report: The patient was a 24-year-old man without any obvious preoperative risk factor for ectasia who underwent bilateral PRK. Four years after keratorefractive surgery, the patient presented with loss of visual acuity (VA) in his right eye. Pentacam findings were persistent with corneal ectasia and Ocular Response Analyzer measurements showed differences in signal shape between two eyes. A single piece intrastromal segment ring was IMPLANTed and ceased the progression of ectasia until now. Conclusion: Corneal ectasia after PRK is extremely rare and can occur without tangible risk factors. Differences between signal shapes in Ocular Response Analyzer and abnormal measurements may be useful in detecting high risk patients. INTACS IMPLANTation appeared to improve ecstatic progressive changes and patient's symptoms.

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 ± 38μm 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.

Background. Modern oral IMPLANTology and IMPLANT prosthetics depend on comprehensive diagnostics and precise planning to ensure the desired outcome and meet the patient’ s and the dentist’ s expectations. Methods. In this context, digital IMPLANT planning and guided IMPLANT surgery based on three-dimensional radiographic data and the digitised intraoral surfaces can be of excellent service. They provide valuable information and permit stringent backward planning to optimise the IMPLANTological and prosthetic result, improving the safety and efficiency of the surgical procedure and rendering the restorative outcome more predictable in terms of function, biology and aesthetics. Results. template-guided IMPLANT surgery carries its own specific risks in terms of manufacturing inaccuracies and application errors. Conclusions. These possible sources of error must be recognised and carefully considered in order to avoid adverse consequences.

This study was performed to evaluate the visual, refractive, and aberration measurement results of 2 IMPLANTs, including INTACS Intracorneal Ring Segments (ICRS) and phakic Toric IMPLANTable Collamer Lens (TICL), in patients with moderate Keratoconus (KCN). In this retrospective cross-sectional study, 30 patients with KCN with a mean age of 29. 83 years were included in 2 groups, including the INTACS Intracorneal Ring Segments (ICRS) group and the phakic Toric IMPLANTable Collamer Lens (TICL) group. Preoperative data as well as 6-month, 1-, 2-, 3-and 4-year follow-up data after the operation were collected and analyzed with the SPSS software (ver. 23. 0, SPSS, Inc., Chicago, IL), using the paired t-test, independent t-test, repeated measures Analysis of Variance (ANOVA), and one-way ANOVA. This study included 30 patients with KCN with a mean age of 29. 83 years and range of 25 to 35 years, including 17 males with a mean age of 30. 11 years and 13 female with a mean age of 29. 25 years. Except for preoperative Uncorrected Distance Visual Acuity (UCDVA), Spherical Equivalent (SE) and astigmatism, there was a significant difference between the 2 groups regarding other variables. The TICL group had a significantly better UCDVA and Best Corrected Distance Visual Acuity (BCDVA) in all post-operative follow-ups, and SE and astigmatism values were significantly lower in all post-operative follow-ups when compared with the ICRS group. There was a significant reduction in corneal and total coma as well as internal trefoil aberrations (P<0. 01, P<0. 01, and P=0. 014, respectively) in the ICRS group, and TICL led to a significant reduction in internal trefoil aberration with P<0. 03. Comparison of the 2 groups revealed a significant difference in corneal spherical (P<0. 01) and total coma (P=0. 02) aberrations and no significant differences in other HOA. Both ICRS and TICL are useful in patients with moderate KCN. However, TICL appears to have more stable and predictable vision results.

The incidence of microbial keratitis after INTACS IMPLANTation is extremely low and channel infection has been infrequently reported. We present a 23-year-old woman with keratoconus of both eyes who underwent IMPLANTation of two intrastromal corneal ring segments (INTACS, KeraVision, Inc., Fremont, CA, USA) in the right eye. After 2.5 months, the patient presented with decreased vision, inflammation, and stromal infiltration at the lower channel site of INTACS. Culture was positive for Escherichia coli. The patient was treated with removing of lower segment of INTACS, and subconjunctival and topical antibiotics. The keratitis resolved, leaving opacity and thinning and mild neovascularization in the lower channel site. Our case report illustrates the risk of microbial keratitis even months after INTACS IMPLANTation. It shows need for long-term postoperative attention by both patient and physician.