Higher incidence of steroid-induced ocular hypertension in keratoconus

Factors influencing haze formation and corneal flattening, and the impact of haze on visual acuity after conventional collagen cross-linking: a 12-month retrospective study

BACKGROUND

Our aim was to determine associations of pachymetry, keratometry, and their changes with haze formation and corneal flattening after collagen cross-linking, and to analyse the relationship between postoperative haze and visual outcome.

METHODS

Retrospective analysis was performed on 47 eyes of 47 patients with keratoconus using the Pentacam HR Scheimpflug camera before and 1, 3, 6 and 12 months after cross-linking. Corneal backscattered light values in grey scale unit were recorded in the anterior, center and posterior corneal layers and in four concentric rings. Surface area- and thickness-corrected grey scale unit values were assessed with an additional calculation. Friedman test with post hoc Wilcoxon signed-rank test was used to analyse changes in visual acuity, pachymetry, keratometry and densitometry. Spearman's rank correlation test was used to detect correlations of haze formation and corneal flattening with pachymetry, keratometry and their postoperative change. Generalized estimating equations analysis was used to investigate the influence of densitometry values on postoperative visual acuity after controlling for the effect of preoperative keratometry.

RESULTS

One year after treatment, significant flattening was observed in maximum and mean keratometry readings (p < 0.001). Significantly increased densitometry values were observed in three central rings compared to baseline (post hoc p < 0.0125). According to receiver operating characteristic curve, densitometry value of the anterior layer of 0-2 mm ring was the most characteristic parameter of densitometry changes after cross-linking (area under the curve = 0.936). Changes in haze significantly correlated with preoperative maximum keratometry (R = 0.303, p = 0.038) and with the changes in maximum keratometry (R = -0.412, p = 0.004). Changes in maximum keratometry correlated with preoperative maximum keratometry (R = -0.302, p = 0.038). Postoperative haze had a significant impact on uncorrected and best corrected distance visual acuity (β coefficient = 0.006, p = 0.041 and β coefficient = 0.003, p = 0.039, respectively).

CONCLUSIONS

Our findings indicate that in more advanced keratoconus more significant corneal flattening effect parallel with haze formation can be observed after cross-linking. Despite significant reduction of keratometry, postoperative corneal haze may limit final visual acuity.

A Novel CD147 Inhibitor, SP-8356, Attenuates Pathological Fibrosis in Alkali-Burned Rat Cornea

The corneal fibrotic responses to corneal damage often lead to severe corneal opacification thereby resulting in severe visual impairment or even blindness. The persistence of corneal opacity depends heavily on the activity of corneal myofibroblast. Myofibroblasts are opaque and synthesize a disorganized extracellular matrix (ECM) and thus promoting opacification. Cluster of differentiation 147 (CD147), a member of the immunoglobulin superfamily, is known to play important roles in the differentiation process from fibroblast to myofibroblast in damaged cornea and may therefore be an effective target for treatment of corneal opacity. Here, we examined the therapeutic efficacy of novel CD147 inhibiting verbenone derivative SP-8356 ((1S,5R)-4-(3,4-dihydroxy-5-methoxystyryl)-6,6-dimethylbicyclo[3.1.1]hept-3-en-2-one) on corneal fibrosis. Topical SP-8356 significantly reduced corneal haze and fibrosis in the alkali-burned cornea. In detail, SP-8356 inhibited both alpha-smooth muscle actin (α-SMA) expressing myofibroblast and its ECM-related products, such as matrix-metalloproteinase-9 and collagen type III and IV. Similar to SP-8356, topical corticosteroid (prednisolone acetate, PA) also reduced the ECM-related products and opacification. However, prednisolone acetate failed to decrease the population of α-SMA-positive corneal myofibroblast. In conclusion, SP-8356 is capable enough to prevent corneal haze by preventing pathological fibrosis after severe corneal damage. Therefore, SP-8356 could be a potentially promising therapeutic drug for corneal fibrosis.

Long-term Outcomes on de novo Ocular Hypertensive Response to Topical Corticosteroids After Corneal Transplantation

PURPOSE

To determine incidence, demographics, management, and outcomes of topical steroid-induced ocular hypertension after penetrating keratoplasty (PKP) and to establish effects on intraocular pressure (IOP) and graft rejection when alternate corticosteroids are used.

METHODS

A single-center, retrospective review of 568 consecutive PKPs performed between 1997 and 2010 was conducted. Data were collected on demographics, best-corrected visual acuity, surgical indications, lens status, IOP, postoperative management, and incidence of rejection.

RESULTS

Eighty eyes (14.1%) of 74 patients were included. The most common indication was keratoconus (28.8%). Twenty-seven eyes (33.8%) were phakic, 46 (57.4%) had a posterior chamber intraocular lens, and 7 (8.8%) had an anterior chamber intraocular lens. Mean postoperative IOP increase was only significant in the anterior chamber intraocular lens group (18.7 mm Hg, SD 10.4; P = 0.02). The average time for developing hypertension was 9.8 months (SD 14.8) postoperatively, with an average IOP increase of 13.3 mm Hg (SD 5.9). Prednisolone acetate 1% was switched to rimexolone 1% in 64 eyes (80%) and to fluorometholone 0.1% in 16 eyes (20%), which alone achieved IOP normalization in 26 eyes (32.5%) (P < 0.01). Fifty-four eyes (67.5%) required additional antiglaucoma medication. An average IOP reduction of 12.3 mm Hg (SD 6.9) was achieved at an average of 2.3 months (SD 5.2) after the switch. Seventeen eyes (21%) developed glaucoma and 13 eyes (16.3%) developed graft rejection after switching formulations, with no statistically significant differences between rimexolone and fluorometholone (P > 0.05).

CONCLUSIONS

The use of alternate topical corticosteroids may be considered in cases of steroid-induced ocular hypertension after PKP because they offer good antiinflammatory prophylaxis with reduced hypertensive response.

Assessment of the Association Between In Vivo Corneal Biomechanical Changes After Corneal Cross-linking and Depth of Demarcation Line

PURPOSE

To test for an association between stiffening following corneal cross-linking (CXL) and demarcation line depth.

METHODS

Sixty-six eyes of 66 patients treated with CXL for progressive keratoconus were included. Dynamic corneal response parameters (DCRs) were measured with the Corvis ST (Oculus Optikgeräte GmbH; Wetzlar, Germany) on the day of CXL and after 1 month. Demarcation line was measured 4 weeks after CXL. A multivariate general linear model was used to test for an association between the change in DCRs and the ratio between demarcation line depth and the postoperative pachymetry.

RESULTS

The authors found no significant associations between the change in inverse concave integrated radius (1/R) and the demarcation line ratio (P = .46), age (P = .33), sex (P = .11), preoperative maximum keratometry (P = .10), and laterality (P = .82). Similarly, there was no significant correlation between the change in 1/R and the demarcation line ratio (R² = .002 and P = .75). However, there was a significant association between the preoperative values of 1/R and the respective change in 1/R (P < .0001). The change in 1/R was inversely proportional to the patient's preoperative 1/R; stiffer corneas (lower values of 1/R) were less affected than less stiff corneas (R² = .23, P < .0001).

CONCLUSIONS

CXL is associated with changes in DCRs, suggesting a change in corneal biomechanics following CXL. These changes do not appear to be associated with the demarcation line depth. [J Refract Surg. 2019;35(3):202-206.].