Corticosteroid-induced intraocular pressure elevation in keratoconus is common following uncomplicated penetrating keratoplasty

Te hauora karu o te iwi Māori: A comprehensive review of Māori eye health in Aotearoa/New Zealand

This article provides a summary of available data on Māori ocular health, highlighting significant disparities between Māori and non-Māori populations. Māori are more likely to develop diabetes, sight-threatening retinopathy and keratoconus, and present for cataract surgery earlier with more advanced disease. Limited data exists for macular degeneration and glaucoma, but there is some suggestion that Māori may have lower prevalence rates. The article emphasises the urgent need for robust national data on Māori ocular health to enable targeted interventions and funding allocation. Achieving equity for Māori in all aspects of health, including ocular health, requires concerted efforts from all stakeholders.

Management of keratoconus: an updated review

Keratoconus is the most common corneal ectatic disorder. It is characterized by progressive corneal thinning with resultant irregular astigmatism and myopia. Its prevalence has been estimated at 1:375 to 1:2,000 people globally, with a considerably higher rate in the younger populations. Over the past two decades, there was a paradigm shift in the management of keratoconus. The treatment has expanded significantly from conservative management (e.g., spectacles and contact lenses wear) and penetrating keratoplasty to many other therapeutic and refractive modalities, including corneal cross-linking (with various protocols/techniques), combined CXL-keratorefractive surgeries, intracorneal ring segments, anterior lamellar keratoplasty, and more recently, Bowman's layer transplantation, stromal keratophakia, and stromal regeneration. Several recent large genome-wide association studies (GWAS) have identified important genetic mutations relevant to keratoconus, facilitating the development of potential gene therapy targeting keratoconus and halting the disease progression. In addition, attempts have been made to leverage the power of artificial intelligence-assisted algorithms in enabling earlier detection and progression prediction in keratoconus. In this review, we provide a comprehensive overview of the current and emerging treatment of keratoconus and propose a treatment algorithm for systematically guiding the management of this common clinical entity.

The effect of loteprednol suspension eye drops after corneal transplantation

BACKGROUND

To compare the effect of loteprednol suspension eye drops after corneal transplantation with the effect of prednisolone acetate eye drops.

METHODS

A total of 234 patients (234 eyes) who underwent penetrating keratoplasty (PKP) and lamellar keratoplasty (LKP) were retrospectively included. Patients who received 1 % prednisolone acetate eye drops were defined as 1 % prednisolone acetate eye drop group (n = 96), and patients who received 0.5 % loteprednol suspension eye drops were defined as 0.5 % loteprednol suspension eye drop group (n = 138).

RESULTS

35 cases in 1 % prednisolone acetate eye drops group and 27 cases in 0.5 % loteprednol suspension eye drops group developed corticosteroid-induced ocular hypertension, and were defined as prednisolone acetate group and loteprednol group. No significant differences were observed in the average intraocular pressure (IOP) at 1 week, 1 month, 3 months or 12 months postoperatively. There were significant differences in the average IOP between the two groups at 6 months postoperatively (P = 0.001). There were no significant differences in the average best corrected visual acuity (BCVA) at 1, 3 and 12 months postoperatively between two groups. The average 6-month postoperative BCVA was significantly higher in the prednisolone acetate group than the loteprednol group (P < 0.05). There were no significant differences in the postoperative graft rejection rates between the two groups (P > 0.05).

CONCLUSIONS

0.5 % loteprednol suspension eye drops may be considered for long-term use after corneal transplantation.

Surgery for glaucoma in modern corneal graft procedures

Glaucoma is a common cause of vision loss after corneal transplantion and is considered a major risk factor for graft failure. Glaucoma may be present before corneal transplant surgery, or increased intraocular pressure may develop after keratoplasty in up to one-third of patients. Pre-existing glaucoma should be controlled before keratoplasty, either medically or surgically. For postkeratoplasty increase in intraocular pressure; identifying the risk factors allows appropiate follow-up and management. Patients undergoing anterior lamellar keratoplasty may take advantage of reduced rates of postkeratoplasty glaucoma. Glaucoma also complicates eyes with endothelial keratoplasties, mostly related to management of intraocular pressure spikes derived from anterior chamber air bubbles. Nevertheless, the severity is less, and the intraocular pressure is more easily controlled when compared with penetrating keratoplasty. Adequate management of glaucoma that develops before or after keratoplasty may save eyes from irreversible damage to the optic nerve and increase graft survival.

Predicting factors of ocular hypertension following keratoplasty: Indications versus the procedure

PURPOSE

To assess the incidence of ocular hypertension (OHTN) following penetrating keratoplasty (PKP) versus deep anterior lamellar keratoplasty (DALK) corneal transplant surgeries, and to assess the impact of indication for transplantation versus surgery type on OHTN development.

METHODS

A retrospective study of 76 eyes of 76 patients who underwent PKP or DALK between 1 January 2009 and 1 September 2014. Data included: preoperative intraocular pressure (IOP), indication and type of surgery, post-surgical IOP at 1 to 5, 14 to 21 days, 3, 6 months, 1 year and at the last follow up. Primary outcome was post-operative OHTN (defined as IOP >21 mm Hg).

RESULTS

A total of 13 patients (17.1%) developed OHTN of whom 9 (20.45%) underwent PKP and 4 (12.5%) DALK (p = 0.33). OHTN occurred after an average of 16.46 ± 8.47 months (0.1-58 months). Twenty-one keratoconus patients (39.62%) underwent PKP and 32 (60.37%) underwent DALK. Patients with indications other than keratoconus all underwent PKP. Keratoconus patients were less likely to develop OHTN (9.43% vs 34.78%, p = 0.02). Among patients developing OHTN, mean age of the non-keratoconus group was significantly higher (63.25±16.7 vs 33 ± 10, p = 0.01). No significant difference in OHTN among keratoconus patients undergoing DALK versus PKP (12.5% vs 4.76%, respectively, p = 0.35) was found. PKP was associated with less OHTN in keratoconus eyes (4.76% vs 34.78%, p = 0.02).

CONCLUSION

Patients who underwent keratoplasty due to keratoconus are at a lower risk to develop OHTN than those who underwent surgery for other indications.

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.

The Rapid Transformation of Transplantation for Corneal Endothelial Diseases: An Evolution From Penetrating to Lamellar to Cellular Transplants

The cornea is the major focusing structure of the human eye and the corneal endothelium maintains the relatively dehydrated state of the cornea required for clarity. The endothelial cells respond to disease or injury by migration and cellular enlargement. Our current understanding is that there is a very limited degree of proliferative or regenerative capacity in the human corneal endothelium. Thus, corneal endothelial diseases may result in corneal edema, significantly impact vision and quality of life. Contemporary surgical transplantation options for treating moderate to advanced endothelial dysfunction include penetrating keratoplasty (PK), Descemet stripping endothelial keratoplasty (DSEK), and Descemet membrane endothelial keratoplasty. Advances in surgical techniques aim to bring faster visual recovery and improve visual outcomes; however, there is still a significant donor cornea shortage worldwide and alternative methods for treatment for corneal endothelial disease are rapidly evolving. Indeed, we are at a pivotal point in corneal transplantation for endothelial disease and novel surgical strategies include using 1 donor for multiple recipients, a minimally attached endothelial graft, and Descemet membrane stripping only. Crucially, forthcoming approaches include the use of Rho-Kinase (ROCK) inhibitors, endothelial cell therapy, tissue engineered grafts, and consideration of stem cell techniques. Ultimately, the choice of technique will be dependent on recipient factors such as age, type of endothelial disease, extent of the disease, and associated ocular disorders. The safety and efficacy of these rapidly developing treatments warrant further investigations. In time, some or all of these alternatives for corneal transplantation will alleviate the reliance on limited corneal donor tissue.

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.

Glaucoma after corneal replacement

Glaucoma is a well-known complication after corneal transplantation surgery. Traditional corneal transplantation surgery, specifically penetrating keratoplasty, has been slowly replaced by the advent of new corneal transplantation procedures: primarily lamellar keratoplasties. There has also been an emergence of keratoprosthesis implants for eyes that are high risk of failure with penetrating keratoplasty. Consequently, there are different rates of glaucoma, pathogenesis, and potential treatment in the form of medical, laser, or surgical therapy.

Tonometry after Intrastromal Corneal Ring Segments for Keratoconus

SIGNIFICANCE

Reliable intraocular pressure (IOP) measurement after intrastromal corneal ring segments (ICRS) implantation is a challenge because of altered corneal morphology. In this study, IOP is measured with four tonometers, compared with Goldmann applanation tonometry (GAT) values and the influence of corneal parameters is established.

PURPOSE

This study compares IOP measurements made using different tonometers in patients implanted with ICRS and assesses the effects of central corneal thickness (CCT), corneal curvature, and corneal astigmatism on the IOP measurements obtained.

METHODS

In this cross-sectional study, IOP was measured using three different tonometers in 91 eyes of 91 patients with corneal ectasia implanted at least 6 months previously with ICRS. The tonometers tested were the TonoPen XL, Pascal dynamic contour tonometer (DCT), and iCare Pro rebound tonometer. GAT measurements were used as reference. Agreement among the IOPs provided by the different tonometers and the influence of corneal variables on the IOP measurements obtained were assessed using the Bland-Altman method, intraclass correlation coefficients, and multiple linear regression analysis.

RESULTS

Mean IOP differences were GAT versus TonoPen XL -0.8 ± 3.07 mm Hg, GAT versus DCT -1.0 ± 3.26 mm Hg, and GAT versus iCare Pro 0.8 ± 2.92 mm Hg. Our multiple linear regression analysis identified CCT as a confounding factor affecting all the tonometer readings but DCT-IOP.

CONCLUSIONS

In patients fitted with ICRS, IOP measurements made using the iCare Pro and TonoPen XL showed most agreement with GAT. Intraocular pressure measurements made by DCT were unaffected by corneal topographic factors though this procedure slightly overestimated GAT readings.

Measuring Intraocular Pressure in Patients With Keratoconus With and Without Intrastromal Corneal Ring Segments

PURPOSE

To compare intraocular pressure (IOP) measurements made using 5 tonometers in keratoconic eyes with and without intrastromal corneal ring segments.

METHODS AND PATIENTS

This was an observational case series study. A total of 147 eyes of 147 patients with keratoconus, 74 of which had undergone corneal ring segment placement, were prospectively evaluated. IOP was measured using the tonometers Tonopen XL, Pascal dynamic contour tonometer, iCare Pro, ocular response analyzer (ORA), and Goldmann applanation (GAT) in random order. The Bland-Altman method was used to examine interinstrument agreement. Effects on readings of central corneal thickness, corneal curvature, and corneal astigmatism were assessed by multivariate regression analysis.

RESULTS

Smallest mean IOP differences with GAT measurements in eyes without and with ring segments, respectively, were detected for iCare Pro [0.2 (2.9) mm Hg and 0.4 (3.0) mm Hg, P=0.914] and greatest differences for ORA Goldmann-correlated IOP [5.8 (3.3) mm Hg and 6.0 (3.1) mm Hg, P=0.363]. Best agreement with GAT was shown by iCare Pro (ICC=0.829; 95% CI, 0.721-0.896) and worse agreement by ORA corneal-compensated IOP (ICC=-0.145; 95% CI, -0.826 to 0.283). All but the dynamic contour tonometer readings were influenced by central corneal thickness, yet these measurements were affected by the presence of ring segments (P=0.017) and corneal astigmatism (P=0.030). Corneal curvature only affected ORA Goldmann-correlated IOP (P=0.029).

CONCLUSIONS

All 5 tonometers provided reliable IOP readings in the keratoconic eyes regardless of the presence of corneal ring segments. iCare Pro readings were most consistent with GAT, whereas ORA readings were least consistent with this reference standard.

Contemporary Treatment Paradigms in Keratoconus

The past 20 years have witnessed an explosion in our knowledge of keratoconus, accompanied by a radical transformation of management options. A 2-hit hypothesis proposes an underlying genetic predisposition coupled with external environmental factors, including eye rubbing and atopy. The variable prevalence and natural history have been better defined including significant cone progression in middle age. Therefore, current management must include early diagnosis, regular monitoring, and treatment of environmental cofactors. Spectacles and contact lenses remain fundamental to the optical management of keratoconus. Intrastromal corneal ring segments have been increasingly used, providing improvement in the corneal shape, corrected visual acuity, and contact lens wear. However, like contact lenses, intrastromal corneal ring segments do not treat the underlying disease process. Therefore, current approaches must also consider treatments to minimize keratoconus progression. Fortunately, there is increasing evidence that corneal collagen crosslinking will halt or slow progression in most cases. Until relatively recently, penetrating keratoplasty was the preferred intervention for advanced keratoconus, with long-term success in the region of 90%; however, the greatest risk of failure remains endothelial allograft rejection. Deep anterior lamellar keratoplasty has emerged in the new millennium as a preferred approach to conserve the host endothelium and avoid rejection. Nonetheless, the overall superiority of deep anterior lamellar keratoplasty compared with penetrating keratoplasty, in terms of optical and survival benefits, is still debated. This perspective provides an overview of our current knowledge of keratoconus and current management options. A step-ladder approach to managing keratoconus is outlined to provide the practitioner with a contemporary management paradigm.

Corneal transplantation and glaucoma

Glaucoma is the leading cause of irreversible vision loss post-keratoplasty and an important cause of graft failure. With newer techniques, such as lamellar, endothelial, and laser-assisted keratoplasty as well as keratoprosthesis gaining popularity, clinicians will need to consider the incidence, risks, evaluation, and management of glaucoma for each type of keratoplasty when determining which type of transplant may be most appropriate. A comprehensive literature search of glaucoma in the setting of corneal transplantation was performed and serves as the basis for this review. Preexisting glaucoma and aphakia are notable risk factors. Patients that are candidates for deep anterior lamellar keratoplasty may benefit from reduced rates of post-keratoplasty glaucoma. Although glaucoma also complicates eyes with Descemet stripping endothelial keratoplasty, the severity is less and the intraocular pressure is more easily controlled when compared to penetrating keratoplasty. Endothelial keratoplasty creates unique perioperative issues mostly related to management of anterior chamber air bubbles.

Treatment options for advanced keratoconus: A review

Traditionally, the mainstay of treatment for advanced keratoconus (KC) has been either penetrating or deep anterior lamellar keratoplasty (PK or DALK, respectively). The success of both operations, however, has been somewhat tempered by potential difficulties and complications, both intraoperatively and postoperatively. These include suture and wound-healing problems, progression of disease in the recipient rim, allograft reaction, and persistent irregular astigmatism. Taken together, these have been the inspiration for an ongoing search for less troublesome therapeutic alternatives. These include ultraviolet crosslinking and intracorneal ring segments, both of which were originally constrained in their indication exclusively to eyes with mild to moderate disease. More recently, Bowman layer transplantation has been introduced for reversing corneal ectasia in eyes with advanced KC, re-enabling comfortable contact lens wear and permitting PK and DALK to be postponed or avoided entirely. We offer a summary of the current and emerging treatment options for advanced KC, aiming to provide the corneal specialist useful information in selecting the optimal therapy for individual patients.

Bilateral juvenile onset primary open-angle glaucoma among keratoconus patients

PURPOSE

To report the occurrence of juvenile open-angle glaucoma (JOAG) in patients with keratoconus.

PATIENTS AND METHODS

In this observational case series we report 6 eyes of 3 patients with keratoconus who had concomitant JOAG. Corneal topography, intraocular pressure, gonioscopic, and fundus findings were recorded for all the eyes.

RESULTS

All 3 patients presented with corneal ectasia, high intraocular pressure, and advanced glaucomatous damage and had no family history of glaucoma or keratoconus. Two of the 3 patients needed collagen cross-linking with riboflavin for progression of keratoconus and trabeculectomy for control of intraocular pressure. One of the patients also underwent a lamellar keratoplasty for keratoconus.

CONCLUSIONS

This is the first case series pointing toward a possible association of JOAG with keratoconus and highlights the importance of a thorough workup of glaucoma in patients with keratoconus.

Understanding keratoconus: what have we learned from the New Zealand perspective?

Although first described more than 150 years ago, keratoconus is still an enigmatic disease that remains an area of wide-ranging, dynamic, international research. This review considers data from New Zealand/Aotearoa, where keratoconus is both relatively common and extensively studied. New Zealand researchers have made several significant contributions to the international literature in this field, including identifying a higher prevalence of keratoconus in New Zealand per se and within Maori and Polynesian populations compared to many international studies. As reported in other studies, a higher proportion of asthma, allergy and eczema as potential risk co-factors are present in New Zealand subjects with keratoconus compared with estimates from the general population. The rates of family history of keratoconus are typically higher than those reported internationally, with higher rates in Asian, Pacific and Maori ethnicities. Interestingly, such a positive family history has been associated with less severe keratoconus on computerised topographic analysis. Investigations of corneal microstructure have revealed dramatic alterations in the keratoconic cornea, with reduced density and abnormal morphology of the corneal sub-basal nerve plexus and decreased keratocytic density. Laboratory studies of keratoconic corneal buttons have also furthered our understanding of the pathophysiology of this disease, demonstrating elevated levels of cathepsin enzymes and localised disruptions in Bowman's layer with incursion of cellular processes from anterior keratocytes. Over the past two decades keratoconus has consistently remained the leading indication for corneal transplantation in New Zealand, accounting for over 40 per cent of cases. Indeed, New Zealand appears to have the highest reported proportion of transplantation surgery for keratoconus worldwide. Current and future studies of keratoconus in New Zealand highlight an emphasis on elucidating the genetics of, and investigating novel therapeutic interventions for, this relatively common corneal disease.

Comparison of intraocular pressure measurement using 4 different instruments following penetrating keratoplasty

PURPOSE

To compare intraocular pressure (IOP) measurements after penetrating keratoplasty (PK) using Goldmann applanation tonometry (GAT; Haag-Streit USA), TonoPen XL (Reichert Inc), Pascal Dynamic Contour tonometer (PDCT; Swiss Microtechnology AG), and Ocular Response Analyzer (ORA; Reichert Inc) and to analyze effects and correlation of corneal thickness and curvature on these measurements.

DESIGN

Prospective, cross-sectional study.

METHODS

SETTINGS

Departments of Ophthalmology, University of Auckland and Auckland District Health Board, New Zealand.

STUDY POPULATION

Thirty-one eyes of 31 participants with previous PK.

OBSERVATIONS

IOP measured using GAT, TonoPen, PDCT, and ORA. Central corneal thickness (CCT) and corneal astigmatism were assessed by Pentacam rotating Scheimpflug tomography.

MAIN OUTCOME MEASURE

Degree of agreement in IOP measures and correlation with CCT and corneal astigmatism.

RESULTS

Mean age was 44.5 ± 21.0 years and mean time since PK was 27.7 ± 28.2 months (range 3.0-122.4 months). Mean CCT was 585 ± 149 μm and mean corneal astigmatism 5.5 ± 3.8 diopters. There was no significant difference in IOP measured by GAT and TonoPen; however, both PDCT (2.12 mm Hg, P < .01) and ORA (6.29 mm Hg, P < .01) measured significantly higher IOPs compared to GAT. ORA showed the least agreement with GAT. Significant correlation was identified between each pair of measurement techniques. No instruments correlated significantly with CCT. Only PDCT showed no significant correlation with corneal astigmatism. However, no IOP measures correlated with corneal astigmatism if sutures in situ or less than 1 year post-PK.

CONCLUSIONS

TonoPen or PDCT are the most suitable alternatives for measuring IOP in PK eyes where GAT readings are difficult to obtain. PDCT also offers the advantage of being independent of both CCT and corneal astigmatism.

Glaucoma and corneal transplant procedures

Glaucoma after corneal transplantation is a leading cause of ocular morbidity after penetrating keratoplasty. The incidence reported is highly variable and a number of etiologic factors have been identified. A number of treatment options are available; surgical intervention for IOP control is associated with a high incidence of graft failure. IOP elevation is less frequently seen following deep anterior lamellar keratoplasty. Descemet's striping-automated endothelial keratoplasty is also associated with postprocedure intraocular pressure elevation and secondary glaucoma and presents unique surgical challenges in patients with preexisting glaucoma surgeries. Glaucoma exists in up to three-quarters of patients who undergo keratoprosthesis surgery and the management if often challenging. The aim of this paper is to highlight the incidence, etiology, and management of glaucoma following different corneal transplant procedures. It also focuses on the challenges in the diagnosis of glaucoma and intraocular pressure monitoring in this group of patients.

Glaucoma and corneal transplant procedures

Glaucoma after corneal transplantation is a leading cause of ocular morbidity after penetrating keratoplasty. The incidence reported is highly variable and a number of etiologic factors have been identified. A number of treatment options are available; surgical intervention for IOP control is associated with a high incidence of graft failure. IOP elevation is less frequently seen following deep anterior lamellar keratoplasty. Descemet's striping-automated endothelial keratoplasty is also associated with postprocedure intraocular pressure elevation and secondary glaucoma and presents unique surgical challenges in patients with preexisting glaucoma surgeries. Glaucoma exists in up to three-quarters of patients who undergo keratoprosthesis surgery and the management if often challenging. The aim of this paper is to highlight the incidence, etiology, and management of glaucoma following different corneal transplant procedures. It also focuses on the challenges in the diagnosis of glaucoma and intraocular pressure monitoring in this group of patients.