Central versus paracentral cone location and outcomes of accelerated cross-linking in keratoconus patients

Serrao

2022

Cornea

Purpose:The scope of this study was to investigate keratoconus progression using zonal average analysis of corneal tomography.Methods:The corneal tomographies of patients participating in initial baseline and all scheduled follow-up visits up to 4 years were analyzed. Data were exported in custom software, which delineated 4 zones of analysis and calculated the average values of the anterior and posterior curvature and the average thickness for each zone at each visit. In particular, a 3.1 mm2 area containing the Kmax, termed “keratoconus cone zone,” was defined for assessing disease progression during the follow-up.Results:A total of 201 patients were enrolled in this prospective study. At 4 years, 31% of the eyes (n = 62) had an average increase of ≥1.0 D in the keratoconus cone zone in baseline visit, whereas only 11% of the eyes (n = 22) had ≥1.0 D Kmax increase in the same period. The zonal anterior average curvature (+1.1 D; P < 0.001) and thickness (−14 μm; P < 0.001) values of the keratoconus cone zone progressed significantly during the follow-up. A high correlation was found between the 4-year changes of Kmax and central corneal thickness values and the change of the average anterior curvature and thickness values in the keratoconus cone zone. The posterior cornea did not show significant average changes (<−0.2 D; P > 0.05) during the follow-up.Conclusions:Single-point tomography indexes for keratoconus progression did not capture the overall structure and shape changes of the cornea. It would be recommended to update criteria for keratoconus management including the zonal average analysis of curvature and thickness values for tracking disease progression over observation periods longer than 1 year.

Section: Discussionmentioning

confidence: 99%

Section: Corneal Tomographic Zonal Analysismentioning

confidence: 99%

Long-Term Zonal Average Analysis of Corneal Tomography in Keratoconus Eyes

Serrao

2022

Cornea

“…Two other prospective studies also showed keratoconus stabilisation with improvements in visual acuity after patients received accelerated CXL ( Mimouni et al, 2021 ; Sot et al, 2021 ). Interestingly, Mimouni et al reported that patients with central cones (defined as within the central 3 mm of the cornea) demonstrated greater improvement in best spectacle-corrected visual acuity (0.08 ± 0.02 logMAR, p < 0.001) and myopia (1.27D more reduction) than patients with paracentral cones (within 3–5 mm of the central cornea) ( Mimouni et al, 2021 ). Sot et al , on the other hand, reported that 17.1% of patients in a cohort of 82 eyes treated with accelerated CXL showed signs of progression.…”

Section: Maximising Pharmacokinetic Properties Of Riboflavin/ultraviolet-a In the Treatment Of Keratoconusmentioning

confidence: 91%

Corneal Cross-Linking: The Evolution of Treatment for Corneal Diseases

Lim

et al. 2021

Front. Pharmacol.

Corneal cross-linking (CXL) using riboflavin and ultraviolet A (UVA) light has become a useful treatment option for not only corneal ectasias, such as keratoconus, but also a number of other corneal diseases. Riboflavin is a photoactivated chromophore that plays an integral role in facilitating collagen crosslinking. Modifications to its formulation and administration have been proposed to overcome shortcomings of the original epithelium-off Dresden CXL protocol and increase its applicability across various clinical scenarios. Hypoosmolar riboflavin formulations have been used to artificially thicken thin corneas prior to cross-linking to mitigate safety concerns regarding the corneal endothelium, whereas hyperosmolar formulations have been used to reduce corneal oedema when treating bullous keratopathy. Transepithelial protocols incorporate supplementary topical medications such as tetracaine, benzalkonium chloride, ethylenediaminetetraacetic acid and trometamol to disrupt the corneal epithelium and improve corneal penetration of riboflavin. Further assistive techniques include use of iontophoresis and other wearable adjuncts to facilitate epithelium-on riboflavin administration. Recent advances include, Photoactivated Chromophore for Keratitis-Corneal Cross-linking (PACK-CXL) for treatment of infectious keratitis, customised protocols (CurV) utilising riboflavin coupled with customised UVA shapes to induce targeted stiffening have further induced interest in the field. This review aims to examine the latest advances in riboflavin and UVA administration, and their efficacy and safety in treating a range of corneal diseases. With such diverse riboflavin delivery options, CXL is well primed to complement the armamentarium of therapeutic options available for the treatment of a variety of corneal diseases.

Current Opinion in Ophthalmology

“…Patients with progressive keratoconus should be evaluated for treatment with collagen crosslinking (CCL) or intrastromal corneal ring segment (ICRS) placement prior to cataract surgery to biomechanically strengthen and flatten the cornea, respectively [12,13]. In patients with severe disease, concurrent CCL and ICRS are safe and effective [14].…”

Section: Preoperative Considerationsmentioning

confidence: 99%

“…Studies suggest cone location may be correlated with age and disease severity. Central cones were found more often in younger patients [12], in patients with more severe disease [18], and tended to have greater flattening after CCL compared with peripheral cones [19]. Decentered cones are commonly found in the inferotemporal direction [18,20 & ].…”

Section: Preoperative Considerationsmentioning

confidence: 99%

Cataract surgery considerations in patients with prior history of keratoconus and ectasia

Moshirfar

Ziari

Ronquillo

2022

Purpose of reviewPreoperative workup for cataract surgery in patients with keratoconus poses certain challenges, particularly in patients with moderate-to-severe disease. This review aims to outline the appropriate preoperative, intraoperative, and postoperative considerations and provides an algorithm to help guide the workup prior to surgery.Recent findingsA new system for keratoconus progression and staging has been proposed and additional studies comparing intraocular lens (IOL) formulas calculations and biometry devices have been conducted.SummaryPatients with severe keratoconus have unpredictable results and have an increased risk of a hyperopic refraction postoperatively. Although studies have compared IOL calculation formulas, there is no consensus on management. Clinical considerations and an approach to the workup are presented; however, additional studies are required to determine the most appropriate management of cataracts in severe keratoconus.