Severity Assessment of Acute Hydrops Due to Recurrent Keratoconus after Penetrating Keratoplasty Using Anterior Segment Optical Coherence Tomography

Management of acute corneal hydrops - Current perspectives

Acute corneal hydrops (ACH) is a rare but sight-threatening complication of corneal ectasias. We aim to review the current literature on etiopathogenesis, histology, role of ancillary investigations, management, and outcomes of ACH by classifying the various management strategies based on their site of action and the underlying mechanism. A review of the literature was conducted by searching the following databases: PubMed (United States National Library of Medicine), Embase (Reed Elsevier Properties SA), Web of Science (Thomson Reuters), and Scopus (Elsevier BV) till April 2023. The literature search used various combinations of the following keywords: acute corneal hydrops, keratoconus, ectasia, management, keratoplasty. Nine hundred eighty-three articles were identified based on the above searches. Case reports which did not add any new modality of treatment to the existing literature, articles unrelated to management, those with no full text available, and foreign-language articles with no translation available were excluded. Eventually, 75 relevant articles that pertained to the management of ACH were shortlisted and reviewed. Recent studies have described newer surgical interventions like full-thickness or pre-Descemetic sutures, thermokeratoplasty, and plasma injection that aim to close the posterior stromal break. Posterior lamellar keratoplasties act by replacing the posterior torn Descemet's membrane (DM), and early deep anterior lamellar keratoplasty (DALK) has been attempted to combine the correction of the anatomical defect and visual rehabilitation in a single surgery. These surgical interventions may help by reducing the scarring and increasing the number of patients who can be visually rehabilitated with contact lenses rather than keratoplasty.

Recurrent keratoconus: an analysis of breaks in Bowman's layer in corneal grafts

OBJECTIVE

To study in a masked fashion whether an objective histological feature associated with keratoconus (KCN) occurs in donor corneas in eyes originally receiving a corneal graft for KCN.

METHODS

Two ocular pathologists performed a retrospective masked histological analysis of slides from donor buttons recovered from 21 eyes with a history of KCN undergoing repeat penetrating keratoplasty (failed-PK-KCN), 11 eyes that underwent their first PK due to KCN (primary KCN), and 11 eyes without history of KCN which underwent PK for other conditions (failed-PK-non-KCN). Breaks/gaps in Bowman's layer served as the pathological feature indicative of recurrent KCN.

RESULTS

Breaks in Bowman's layer were present in 18/21 (86%) of the failed-PK-KCN group, 10/11 (91%) of the primary KCN group, and in 3/11 (27%) of the failed-PK-non-KCN group. Pathological evidence suggests that the prevalence of breaks is significantly higher in grafted patients with a history of KCN than non-KCN controls (OR: 16.0, 95% CI 2.63 to 97.2, Fisher's exact test p=0.0018) with a conservative Bonferroni criterion of p <0.017 to account for multiple group comparisons. There was no statistically significant difference found between the failed-PK-KCN and primary KCN groups.

CONCLUSIONS

This study provides histological evidence that breaks and gaps in Bowman's layer, consistent with those found in primary KCN, may develop within the donor tissue in eyes with a history of KCN.

Comparison of Mini-DMEK versus predescemetal sutures as treatment of acute hydrops in keratoconus

PURPOSE

To compare two surgical treatment options for acute corneal hydrops in keratoconus: Mini-DMEK versus predescemetal sutures.

METHODS

Sixteen patients were treated by either Mini-Descemet membrane endothelial keratoplasty (Mini-DMEK) (n = 7, group 1) or predescemetal sutures (n = 9, group 2) early after onset of acute hydrops. Visual acuity, maximum corneal thickness (SD-OCT) in the affected oedematous area, complications and recurrence rates were retrospectively compared between both groups. Measurements were taken immediately preoperatively as well as 1 day, 1 week and 1 month postoperatively (Table 1).

RESULTS

Both groups showed reductions in corneal thickness and increased visual acuity shortly after surgery. In group 1 (average age 33 years ± 7 years), the best corrected visual acuity (BCVA) increased from logMAR 1.65 ± 0.7 before Mini-DMEK to logMAR 0.93 ± 0.6 30 days after Mini-DMEK (p = 0.046). During that period, maximum corneal thickness decreased from 1159 ± 338 µm before surgery to 531 ± 75 µm after Mini-DMEK (p = 0.046). Patients from group 2 (average age 34 ± 10 years) had a BCVA of logMAR 1.59 ± 0.8 which increased to logMAR 0.97 ± 0.5 (p = 0.014) 30 days after surgery. At the same time, the preoperative maximum corneal thickness decreased from 1439 ± 272 µm to 476 ± 162 µm (p = 0.014). There was no difference in corneal thickness or BCVA one month after the surgical intervention between both groups (p = 0.394 and p = 0.871).

CONCLUSIONS

Both techniques, Mini-DMEK and predescemetal sutures, are effective in the treatment of an acute hydrops in keratoconus. Mini-DMEK appears to be beneficial in large DM tears.

Acute corneal edema decades after penetrating keratoplasty for keratoconus in eyes wearing scleral contact lenses

PURPOSE

To report three cases of acute corneal edema occurring decades after penetrating keratoplasty (PK) for keratoconus in eyes wearing scleral contact lenses (ScCLs) with previously clear corneal grafts.

METHODS

Retrospective chart review of three ScCL wearers presenting for sudden onset pain and blurred vision. Data extracted included clinical presentation, year and reason for PK, ocular medications and comorbidities, contact lens wearing history, results of any ancillary testing available including corneal topography, anterior segment optical coherence tomography (OCT), and specular microscopy surrounding the event, treatment and outcomes of intervention. The number of PK eyes fit with ScCLs in the author's practice was determined to estimate the prevalence of this event.

RESULTS

The three patients each had a longstanding PK for keratoconus performed between 33-35 years prior to presentation and recurrent ectasia. Each patient presented with an acute, painful eye and reduced vision either 3 days, 4 months or 9 years after refitting into ScCLs. Each eye had well demarcated focal microcystic epithelial and stromal edema within the graft and crossing the wound margin onto the host cornea. Although a definitive break or detachment of Descemet's membrane was not visualized, the presentations suggest these were episodes of acute hydrops.

CONCLUSIONS

Longstanding PKs with recurrent ectasia and acute focal edema suggestive of corneal hydrops is demonstrated in this case series of ScCL wearers. Although similar events have occurred as part of the natural history of post-PK corneas for keratoconus, the proximity of ScCL refitting to two of the events suggests some association.

Risk factors and evaluation of keratoconus progression after penetrating keratoplasty with anterior segment optical coherence tomography

To determine the risk factors and unique characteristics of keratoconus (KC) progression after penetrating keratoplasty (PK), anterior segment optical coherence tomography parameters were statistically analyzed in comparison with eyes undergoing PK for other diseases as a control. Ninety-one eyes maintaining clear PK grafts for over 10 years were divided into 2 groups according to the primary indication for PK (KC vs Others groups). Corneal thinning indicators (inferior host thinnest corneal thickness/central corneal thickness [IHT/CCT], inferior graft thinnest corneal thickness/CCT [IGT/CCT]), were smaller whereas anterior chamber depth, and steepest corneal power (Ks), and maximum corneal power (K_max) were larger in the KC group with statistical significance. Graft size, K_max and Ks correlated with IHT/CCT and IGT/CCT in the KC group. These correlations were not detected in controls. Graft size and postoperative period were selected by multivariate regression analysis as factors for corneal ectatic changes in the KC group. In conclusion, KC eyes long after PK show inferior graft and host corneal thinning, and corneal protrusion. Corneal power parameters such as K_max or Ks can be used to monitor KC progression after PK. A small graft might lead to KC progression after PK.

Corneal topography in keratoconus evaluated more than 30 years after penetrating keratoplasty: a Fourier harmonic analysis

The aim of this observational study was to examine the characteristics of anterior and posterior corneal topography in keratoconic eyes more than 30 years after penetrating keratoplasty (PK). Patients who maintained clear grafts for more than 30 years after PK were included and divided into the keratoconus (KC) group or other diseases (Others) group, based on the primary indication. Twenty-six eyes of 26 patients were included. The KC group and the Others group included 14 eyes and 12 eyes, respectively. The KC group participants were younger at the time of surgery (P = 0.03). No differences were found in best-spectacle-corrected visual acuity, keratometric power, and central-corneal-thickness. Based on corneal topography using Fourier harmonic analyses, regular astigmatism in the anterior cornea was significantly larger (P = 0.047) and the spherical component in the posterior cornea was significantly lower (P = 0.01) in the KC group. The area under the receiver operating characteristic curve of the spherical component, regular astigmatism, asymmetry component, and higher-order irregularity were 66.07%, 63.10%, 57.14%, and 59.23%, respectively, in the anterior cornea and 80.65%, 52.98%, 63.10%, and 63.99%, respectively, in the posterior cornea. Our results suggested that Fourier harmonic analysis of corneal topography could be useful for patients with KC long after PK.