Aim: The aim of the study was to assess the morphological changes in animal corneas following local cross-linking (CXL). Materials and methods: Experimental comparative study included nine isolated porcine eyeballs (ex vivo group) and nine Chinchilla rabbits, one eye per animal (in vivo group). All the corneas in both groups were saturated with 0.1% riboflavin and corneal CXL was performed with Locolink device (Transkontakt, Russia), a system that allows to deliver ultraviolet (UV) radiation through a mask of any pattern. One half of each cornea was cross-linked and the other half remained intact. Three corneas of each group were irradiated according to the standard Dresden protocol with 3.0 mW/cm² for 30 minutes (5.4 J); yet, three corneas were irradiated in accelerated CXL mode I with 6.0 mW/cm² for 15 minutes (5.4 J), and yet, three corneas were treated in accelerated CXL mode II with 5.0 mW/cm² for 10 minutes (3.0 J). In the ex vivo group, the corneas of the whole isolated porcine eyeballs were examined with optical coherence tomography (OCT): The stromal demarcation line depth was evaluated by 10 different topographical points per image and the optical density of the corneal layers over the demarcation line was evaluated qualitatively as positive or negative. In the In vivo group, the rabbits were sacrificed 5 days after treatment, and their eyes were enucleated. Corneoscleral buttons were excised and subjected to histological and transmission electron microscopy (TEM) examination. Results: Ex vivo group: Ultrastructural examination and OCT imaging showed that the demarcation line was more superficial after accelerated CXL than after standard CXL. In vivo group. No histological change was detected in the intact area. The re-epithelialization was complete by 72 hours after the procedure. Ultrastructural and histological examination on day 5 following complete re-epithelialization of the cornea showed the presence of bridge-like chains forming cross-links between collagen fibrils in tangential sections. Keratocytes in irradiated zones were either in the state of apoptosis or were activated and produced newly formed collagen. Conclusion: The method of local CXL allows to accurately and selectively modify limited regions of the cornea leaving other areas intact. In the case of local irradiation of the cornea, UV structural changes occur only within the irradiated area. The optimal protocol for use in local CXL is the Dresden protocol.

Aim: To analyze the clinical and functional outcomes of correction of high myopia in eyes with the first stage of keratoconus using femtosecond laser-assisted intrastromal MyoRing implantation. Materials and methods: Thirty eyes (15 patients) with the first stage of keratoconus and high myopia underwent femtosecond laser-assisted intrastromal MyoRing implantation. Mean corneal thickness was 468 ± 12.4 μm. MyoRings were inserted in the intrastromal pockets with diameter 9.0 mm at the depth of 300 μm using femtosecond laser IntraLase FS 60 kHz. Results: Mean uncorrected visual acuity (UCVA) value increased from 1.2 ± 0.03 to 0.3 ± 0.1 logMAR 6 months after operation, mean best corrected visual acuity (BCVA) value increased from 0.24 ± 0.09 to 0.18 ± 0.03 logMAR. Then UCVA and BCVA values remained practically unaltered during the whole follow-up period. Conclusion: The MyoRing implantation stabilizes the keratoconus by enhancing the biomechanical properties of the cornea and simultaneously improves visual acuity due to correction of high myopia.

Aim: To evaluate possible correlation of cone eccentricity and visual acuity in inferior and central keratoconus patients following Keraring implantation for keratoconus. Materials and methods: A total of 19 eyes from an equal number of patients were analyzed in this preliminary pilot retrospective study. Two groups were formed, group I for inferior (n = 11) and group II for central keratoconus (n = 9). Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), keratometric readings, central corneal thickness, maximum keratometric distance from corneal apex (DKmax), and corneal thinnest point from corneal apex (DTh) were evaluated preoperatively and 6 months after the Keraring implantation. The DKmax and DTh were measured and from corneal apex to evaluate the eccentricity of the cone. Results: The CDVA and refractive cylinder reduction improved at 6 months postoperatively in both groups (t-test, p = 0.002, p < 0.0001 and p = 0.0007, p = 0.0017 respectively). Topography keratometric findings (Kmax difference) and spherical equivalent improved for group II but not for group I (t-test, p = 0.002, p = 0.005 and p = 0.85, p = 0.12 respectively). There was a high correlation between CDVA and corneal astigmatic reduction (p = 0.0283, correlation coefficient r = -0.7) and a negative relation in regression analysis (p = 0.0240, y = 0.2616 + - 0.1354 × + 0,03750 × 2, coefficient of determination R² = 0.7115) for the central keratoconus but not for the inferior one. There was no correlation between the topography landmarks DKmax or DTh and CDVA and no statistical difference was found between them in t-test at 6 months. Conclusion: Both groups profited from a Keraring implantation in terms of CDVA, but a relation between corneal astigmatic reduction and CDVA after Keraring implantation at 6 months was found only in patients with central keratoconus. Clinical significance: This finding suggests that a visual acuity improvement in keratoconus patients is not only topographic and keratometric-related but also higher order aberration reduction-dependent. Bigger prospective studies that also evaluate corneal aberration reduction findings are needed to support our results.

Aim: To evaluate corneal biomechanical properties in myopic (MY), hyperopic (HY), and keratoconic (KCN) eyes as measured with the Corvis ST, a newly developed Scheimpflugbased noncontact tonometer with features of visualization and measurement of the corneal deformation response to an air impulse. Materials and methods: Corneal biomechanical properties measurements were obtained for 34 KCN, 109 MY, and 12 HY patients. Statistical analysis was performed using logistic regression in order to control for confounders (intraocular pressure, pachymetry, and first applanation time) and to identify optimal combinations of parameters for KCN detection. Results: No single parameter was significantly different between KCN and either MY or HY after controlling for cofounders. The two combinations of parameters that were assessed achieved low specificity and sensitivity values. Conclusion: The parameters and their combinations overlapped significantly between the groups and could not provide an adequate means to differentiate KCN from healthy corneas. Therefore, with regard to KCN, the Corvis ST can only be used as an adjunct to the clinical examination and customary diagnostic tools.

Background: The two most important goals of management of keratoconus and other corneal ectatic diseases are halting disease progression and visual rehabilitation. Several treatment strategies to skip corneal transplantation have been developed but controversies of the best treatment option for a given patient still exist. The combination of CXL and PIOL implantation has been proposed for visual rehabilitation in patients with progressive keratoconus. Aim: To review the published clinical evidence on the combination of corneal cross-linking (CXL) and phakic intraocular lenses (PIOLs) in patients with keratoconus. Results: No randomized controlled trials and only four retrospective case series were identified. The progression of keratoconus was stopped in all eyes and satisfactory visual rehabilitation was achieved both in terms of uncorrected and corrected distance visual acuity (CDVA) and predictability of refractive correction. Conclusion: Corneal cross-linking combined with PIOL implantation is a valid therapeutic approach for progressive keratoconus with moderate-to-high refractive errors, regular or mildly irregular astigmatism, and good CDVA, especially in the face of significant anisometropia. Clinical significance: The combination of CXL and PIOL implantation is a valid therapeutic approach for visual rehabilitation of progressive keratoconus. Although longer-term follow-up clinical data from prospective randomized clinical trials (RCTs) are needed, clinical outcomes are excellent and equivalent to nonkeratoconic eyes up to 3 years after surgery.

Keratoconus (KC) is the most common corneal ectatic disorder characterized by asymmetric cone-shaped corneal protrusion. The pathophysiology of KC is still unclear. For many years, KC has been considered as a noninflammatory degenerative disease. However, several studies suggested that inflammatory mediators play a role in KC pathogenesis. Tear film contains various mediators that reflect ocular surface diseases. Monitoring the changes in tear composition can be used as a diagnostic tool. In this review, the adequacy of tear markers in the diagnosis of KC was discussed.

In this review/opinion article, we prospectively discuss the evolution of knowledge related to keratoconus and ectatic corneal diseases (ECDs), which is intimately related to the emergence of modern refractive surgery in the early 1980s. This is linked, but goes further beyond the need for screening candidates at risk for progressive keratectasia prior to refractive laser vision correction (LVC). In this scenario, we evolved from early diagnosis of keratoconus toward the characterization of the individual susceptibility for ectasia development. There was a paradigm shift related to the management of ECDs, which was unsophisticated and limited to spectacles, rigid contacts lens, or penetrating keratoplasty (PKP). In fact, the emergence of novel treatment modalities, such as corneal cross-linking (CXL) and intrastromal corneal ring segments (ICRS), has established conflicting situations on when, why, and how to proceed with surgery on these patients. Such paradoxes determine the need for individualized treatment planning, which should consider accurate evaluation of patient needs, advanced imaging with advanced geometric characterization, biomechanical assessment, and environmental factors. In addition, patient (and family) education has become an essential part of the management in order to allow conscious decisions and set realistic expectations. In addition, explaining patients that eye rubbing is a major factor on ectasia progression has gained its momentum with the JUNE VIOLET campaign. Such enhanced understanding has led “corneal ectasia” to be considered as a novel subspecialty in ophthalmology.

This review provides information about MyoRing treatment of keratoconus (KC). MyoRing is a complete ring implant that is inserted into the cornea via a narrow lamellar entrance between two corneal layers at 300 μm depth beneath the corneal surface. Since MyoRing is a complete ring it can achieve both visual rehabilitation and stop of progression. The procedure is very safe and effective and lasts only 10 to 15 minutes. It is performed under topical anesthesia and is intra- as well as postoperatively free of pain. Complications are extremely rare.

Aim: To report a case of bilateral post-laser in situ keratomileusis (LASIK) ectasia associated with pigmentary glaucoma (PG), in which intraocular pressure (IOP) assessment had been relentlessly underestimated by Goldmann's applanation tonometry (GAT). Materials and methods: Case report and prospective literature review. Results: The patient presented for second opinion regarding ectasia in the right eye, while ectasia was diagnosed in the left eye. Uncorrected visual acuity was 20/40 oculus dexter (OD) and 20/200 oculus sinister (OS). Distance corrected visual acuity was 20/20 in OD and 20/50 OS; GAT was 18/18 mm Hg. Slitlamp biomicroscopy was relevant for a well-positioned superior hinge cornel flap and Krukenberg's spindle in both eyes, and Fleischer's ring in the left eye. Corneal compensated IOP was 47.8 and 43.8 mm Hg in OD and OS as measured by the ocular response analyzer (ORA; Reichert, Buffalo, New York, USA). The biomechanicalcompenated (IOPb) was 62.9 mm Hg OD and unmeasured OS by Corvis ST (Oculus; Wetzlar, Germany), which also demonstrated attenuated corneal deformation OU. Pentacam confirmed corneal ectasia in both eyes, being considerably worse in OS. One day after initiation of a fixed combination of beta blocker and carbonic anhydrase inhibitor, the patient noted significant improvement of vision with reduction of IOPb to 13 and 13.5 mm Hg in OD and OS respectively. Patient referred improvement in quality of vision and there was marked reduction on corneal scatter, thickness, and curvature. Conclusion: Pigment dispersion syndrome (PDS) and PG may coexist with corneal ectasia. Careful consideration of the corneal impact on IOP assessment is mandatory when evaluation patients after laser vision correction (LVC). The IOP normalization may improve corneal ectasia in patients with coexisting glaucoma or ocular hypertension.

Eye rubbing has long been acknowledged as a risk factor for keratoconus (KC), but its role in the pathogenesis of KC may not have been accorded sufficient prominence. This article puts forth the conjecture that KC is not a dystrophy of unknown genetics and biomolecular substratum, but rather a syndrome caused by eye rubbing, i.e., what has been called “keratoconus” is the direct consequence of mechanical trauma to the cornea by chronic and incessant eye rubbing, resulting in the progressive deformation and thinning of the corneal wall, the hallmarks of the disease. The conjecture is challenged in this article to investigate its compatibility with what is currently known about KC. The conjecture does not contradict previous clinical or experimental findings about KC, all of which can be interpreted in light of this proposed mechanism. Rather, it is a synthetic approach that incorporates the results of previous genetic and biochemical perspectives for understanding the pathophysiology of KC. In fact, this mechanical disease proposition would appear more compatible with explaining the variability of KC expression between patients, between eyes, and the predominance of sporadic cases. As such, eye rubbing may not be solely a risk factor as often coined in medical literature, but the direct cause of the syndrome labeled “keratoconus.” In conclusion, this mechanical theory provides a better explanatory framework for what is currently known about KC and confirms the validity of the “no rub, no cone” conjecture.

Aim: To develop a new surgical keratectasia classification. Materials and methods: We did analysis of existing variants of classification of keratectasia, discussion of newly appeared classifications. We discussed advantages and disadvantages of the presented information. We also discussed the decision of a question on creation of the optimum approach to surgical treatment of patients depending on a kind and a stage of keratectasia. Results: Keratectasias were classified according to the presence of the ectatic process progression (progressive and stable); type of ectasia (primary and secondary); ectasia symmetry (symmetrical and nonsymmetrical); stages (0, I, II, III and IV). The following are recommended for each stage: Subclinical stage 0: Observation and check-up every 6 months; stage I: Ultraviolet (UV) cross-linking; stage II: Intracorneal ring segments (ICRS) implantation, UV cross-linking only if residual ametropia correction by photorefractive keratectomy (PRK) or toric intraocular lenses (TIOL) implantation is planned; stage III: Deep anterior lamellar keratoplasty (DALK); stage IV: penetrating keratoplasty (PK). Conclusion: The presented keratectasia classification is based on modern diagnostic methods; it allows to determine the tactic of surgical treatment, depending on the type and stage of the pathological process. Clinical significance: Our classification helps doctors to easily put the stage of keratoconus process and decide on the following surgical treatment.