Topographic, tomographic and biomechanical corneal changes during pregnancy in patients with keratoconus: a cohort study

Chronic intermittent hypoxia modulates corneal fibrotic markers and inflammatory cytokine expression in a sex-dependent manner

Chronic intermittent hypoxia (CIH) is a commonly observed condition in patients suffering from obstructive sleep apnea (OSA). Previous studies link CIH to fibrosis, inflammation, and hormonal dysregulation across various tissues. Yet, the effect of CIH in the cornea is unknown. Moreover, women and men diagnosed with OSA present with diverse symptoms, suggesting sex-specific pathophysiology at play. Thus, we used a rat model to assess the impact of CIH and sex on protein expression of corneal fibrotic markers (α-SMA, COL III, cFN, TSP-1), proinflammatory cytokines (IL-1 α, IL-17, IL-18, and IFN-γ), and hormone receptors (ERα, ERβ, GPER, GnRH-R, and LH-R). Male and female Sprague Dawley rats were exposed to normoxic or CIH conditions during their sleep cycle for 14 days. Extracted corneal proteins were subjected to Western blot and multiplex magnetic bead analysis. Our results reveal sex differences in fibrotic and inflammatory markers in the cornea, whereby female corneas exhibit higher levels of fibrotic markers, while male corneas exhibit increased inflammatory cytokines. CIH exposure resulted in elevated levels of α-SMA and pro-inflammatory cytokines in female corneas, while there was no impact on fibrotic or inflammatory markers in male corneas. Additionally, CIH exposure reduced hormone receptors in male and female corneas in a sex-dependent manner. Correlation analyses identified associations of corneal hormone receptors with corneal fibrotic and pro-inflammatory markers that were dependent on sex, with female corneas demonstrating stronger correlations compared to male corneas. Altogether, our data suggests hormone-mediated signaling may contribute to CIH-mediated corneal fibrosis and inflammatory phenotypes, especially in females.

A State-of-the-Art Review of Ophthalmological Indications for a Cesarean Section: Is There a Patient for Whom a Cesarean Section Is Really Indicated?

Purpose: Our purpose was to review the current literature regarding ophthalmologic indications for cesarean section (CS). Methods: A literature search was conducted using MEDLINE, Embase, and the Cochrane Library from inception through October 2024. The databases were searched using the following keywords: "Caesarean section" OR "Caesarean section" OR "delivery" OR "pregnancy" AND "eyes" OR "eye disorders" OR "ocular disease" OR "diabetic retinopathy" OR "myopia" OR "retinal detachment" OR "glaucoma" OR "keratoconus". Studies were considered eligible if they described pregnancy management in women affected by an eye disorder, with insight into the mode of delivery. Results: A total of 8383 results were identified, including only 1 specific guideline and no randomized controlled trials. After a manual review, 38 manuscripts were selected for inclusion. Based on the available evidence, an elective CS may be considered on a case-by-case basis in the presence of specific ophthalmic conditions, such as high-grade myopia with subretinal neovascularization, proliferative diabetic retinopathy, advanced glaucoma, or advanced keratoconus. These conditions are rare among women of childbearing age. Conclusions: Currently, only a limited number of highly specific ophthalmic conditions may benefit from an elective CS. Considering the potential short- and long-term implications of a CS, and in line with the current World Health Organization recommendations, this surgical procedure should be reserved for cases with a clear indication. Given the paucity of data in the available literature, further prospective randomized controlled trials are necessary to enhance the quality of evidence.

Physiological and pathological changes to the eye and vision during and after pregnancy

Pregnancy introduces a multitude of changes in the body, including hormonal fluctuations and metabolic changes, which can lead to atypical ocular signs and symptoms. Ocular manifestations range from fluctuations in vision, to microstructural changes in the retina and choroid, to dry eye disease. This narrative review highlights the range of pregnancy-related effects on the eye and vision that are likely to present in the context of routine eyecare. Specifically, physiological ocular changes and pathological ocular changes that manifest for the first time, or are exacerbated, in uncomplicated pregnancy are discussed. The literature has evolved from simply noting differences in the eye between pregnant and non-pregnant groups, to refining knowledge of the proposed underlying pathophysiology with the advent of newer technologies in eyecare. A particular focus of this review is navigating when pregnancy changes in the eye occur or peak during the gestational period, and whether the changes are short-lived or might extend past pregnancy. While many pregnancy-associated changes are temporary and resolve post-partum, it is also recognised that some changes persist after pregnancy, with a notable absence of literature on ocular changes with loss or termination of pregnancy. Currently or previously pregnant women (or those planning to become pregnant), and other health professionals, should be educated about the importance of seeking eyecare before, during and after pregnancy.

Keratoconus

Keratoconus is a progressive eye disorder primarily affecting individuals in adolescence and early adulthood. The ectatic changes in the cornea cause thinning and cone-like steepening leading to irregular astigmatism and reduced vision. Keratoconus is a complex disorder with a multifaceted aetiology and pathogenesis, including genetic, environmental, biomechanical and cellular factors. Environmental factors, such as eye rubbing, UV light exposure and contact lens wearing, are associated with disease progression. On the cellular level, a complex interplay of hormonal changes, alterations in enzymatic activity that modify extracellular membrane stiffness, and changes in biochemical and biomechanical signalling pathways disrupt collagen cross-linking within the stroma, contributing to structural integrity loss and distortion of normal corneal anatomy. Clinically, keratoconus is diagnosed through clinical examination and corneal imaging. Advanced imaging platforms have improved the detection of keratoconus, facilitating early diagnosis and monitoring of disease progression. Treatment strategies for keratoconus are tailored to disease severity and progression. In early stages, vision correction with glasses or soft contact lenses may suffice. As the condition advances, rigid gas-permeable contact lenses or scleral lenses are prescribed. Corneal cross-linking has emerged as a pivotal treatment aimed at halting the progression of corneal ectasia. In patients with keratoconus with scarring or contact lens intolerance, surgical interventions are performed.

Decreased Circulating Gonadotropin-Releasing Hormone Associated with Keratoconus

Keratoconus (KC) is a corneal thinning dystrophy that leads to visual impairment. While the cause of KC remains poorly understood, changes in sex hormone levels have been correlated with KC development. This study investigated circulating gonadotropin-releasing hormone (GnRH) in control and KC subjects to determine if this master hormone regulator is linked to the KC pathology. Plasma and saliva were collected from KC subjects (n = 227 and n = 274, respectively) and non-KC controls (n = 58 and n = 101, respectively), in concert with patient demographics and clinical features. GnRH levels in both plasma and saliva were significantly lower in KC subjects compared to controls. This finding was retained in plasma when subjects were stratified based on age, sex, and KC severity. Control and KC corneal fibroblasts (HKCs) stimulated with recombinant GnRH protein in vitro revealed significantly increased luteinizing hormone receptor by HKCs and reduced expression of α-smooth muscle actin with treatment suggesting that GnRH may modulate hormonal and fibrotic responses in the KC corneal stroma. Further studies are needed to reveal the role of the hypothalamic-pituitary-gonadal axis in the onset and progression of KC and to explore this pathway as a novel therapeutic target.

Systemic and Ocular Associations of Keratoconus

Introduction

Keratoconus (KC) is the most prevalent corneal ectasia in the world and its pathogenesis is influenced by both ocular and systemic factors. This review explores the multifaceted associations between keratoconus and systemic health conditions, ocular characteristics, and various other environmental/exogenous factors, aiming to illuminate how these relationships influence the pathophysiology of the disease.

Areas Covered

This review will summarize the fundamental attributes of KC, review and discuss the systemic and ocular association of KC including molecular biomarkers, and provide an organized overview of the parallel alterations occurring within various biological pathways in KC.

Expert Opinion

Despite the substantial volume of research on keratoconus, the precise etiology of the disease remains elusive. Further studies are necessary to deepen our understanding of this intricate disorder and improve its management.

Pregnancy and the eye: What do we need to watch out for? A review

Pregnancy causes changes in all body systems, including the eye. The eye can undergo physiological and pathological changes in pregnancy. Some changes exacerbate pre-existing eye conditions while other conditions manifest for the first-time during pregnancy. Early recognition and management are essential to prevent sight threatening complications. In addition, some obstetric complications can be associated with ophthalmic signs. Prompt recognition of these eye findings may be life saving for both the mother and the foetus. The aim of this article is to present potential ocular complications in pregnancy and outline the appropriate management to preserve sight and maintain maternal and foetal safety. The safety of the use of common ophthalmological medications will also be discussed.

Ethnicity, Progressive Keratoconus, and Outcomes after Corneal Cross-Linking in Southern Israel

PURPOSE

To assess clinical outcomes of corneal cross-linking (CXL) intervention in a population diagnosed with progressive keratoconus.

METHODS

This single-center retrospective cohort study included consecutive patients who underwent standard CXL or accelerated CXL for progressive keratoconus at a major teaching hospital in southern Israel between January 2015 and December 2019. Patients' medical files were reviewed, and pre-operative and post-operative data regarding demographics and clinical and tomographic characteristics were extracted and analyzed.

RESULTS

This study included 166 patients (representing 198 eyes), out of which 98 patients (123 eyes) were ethnically Bedouin, and 68 patients (75 eyes) were ethnically Jewish. Overall, 126 patients (144 eyes) had a follow-up of at least 12 months (16.84 ± 5.76). The mean patient age was 20.62 ± 7.1 years old. There were significant baseline differences between the two ethnic groups in best-corrected visual acuity (BCVA; p < 0.001), uncorrected visual acuity (UCVA; p < 0.001), mean keratometry (p = 0.028), and corneal thickness (p < 0.001). Significant changes in BCVA, UCVA, and pachymetry parameters within each group were found after 12 months. Negative binomial regression analysis showed a maximal keratometry below 55D (RR = 1.247, p < 0.001), and a standard CXL procedure (RR = 1.147, p = 0.041) are significantly related to the stability of KC after 12 months. However, the effect size of the origin of patients is negligible (RR = 1.047, p = 0.47).

CONCLUSIONS

In this study, the Bedouin population suffered from more progressive keratoconus when compared to the Jewish population. CXL was significantly effective in improving BCVA and UCVA in both groups after 12 months of follow-up. The effect size of the origin of patients on the stability of KC was found to be negligible.

Selective Modulation of the Keratoconic Stromal Microenvironment by FSH and LH

Keratoconus (KC) affects the corneal structure, with thinning and bulging outward into a conelike shape. Irregular astigmatism and decreased visual acuity appear during puberty and progress into the mid-30s, with unpredictable disease severity. The cause of KC is recognized as multifactorial, but remains poorly understood. Hormone imbalances are a significant modulator of the onset of KC. This study sought to investigate the role of gonadotropins, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) in KC, using a three-dimensional, self-assembled matrix in vitro model. Healthy corneal fibroblasts and human KC cells in the corneal stroma were isolated, cultured, and stimulated with stable vitamin C to promote extracellular matrix assembly. Cultures were further stimulated with 2.5 or 10 mIU/mL FSH and 5 or 35 mIU/mL LH. Samples were evaluated for cell proliferation and morphology via BrdU assay and imaging; protein expression was assessed via Western blot analysis. Proliferation was significantly greater in human KC cells compared to healthy corneal fibroblasts with LH stimulation, but no changes were found with FSH stimulation. Additionally, in sex hormone receptors, fibrotic markers, proteoglycans, and members of the gonadotropin signaling pathway were significantly changed, largely driven by exogenous LH. The impact of exogenous FSH/LH in the KC stromal microenvironment was demonstrated. These results highlight the need to further examine the role of FSH/LH in KC and in human corneal homeostasis.

The effects of female sex hormones on the human cornea across a woman's life cycle

The cornea is a hormone-responsive tissue that responds to changing levels of female sex hormones. This review focuses on the structural and functional changes in the human cornea associated with the hormonal milestones of menarche, pregnancy, and menopause, as well as consequences stemming from the use of exogenous sex hormones for fertility control and replacement. Articles were identified by searching PubMed without language or region restrictions. The primary outcomes evaluated were changes in central corneal thickness (CCT), intraocular pressure (IOP), and quality of the ocular tear film. The potential impact of hormone-associated changes on the diagnosis and surgical management of common eye diseases, as well as the potential use of sex hormones as therapeutic agents is also considered. Understanding the physiological effects of female sex hormones on the cornea is important because that knowledge can shape the management decisions physicians and women face about ocular health across their life stages.

Possible association of keratoconus progression with gender-affirming hormone therapy: A case report

Purpose

To present a case of keratoconus progression following gender-affirming hormone therapy.

Observations

A 28-year-old male-to-female transgender patient with potential past ocular history of subclinical keratoconus presented with subacute worsening myopia of both eyes (OU), 4 months after initiation of gender-affirming hormone therapy. A diagnosis of keratoconus was established based on slit-lamp exam and computerized corneal tomography. Notable indices were central corneal thinning and inferior steepening OU with maximum corneal curvatures of 58.3 D of the right eye (OD) and 77.7 D of the left eye (OS) and thinnest corneal thickness of 440 μm OD and 397 μm OS. After 8 months of continued hormone therapy, the patient's keratoconus continued to progress and thus corneal crosslinking was recommended and performed.

Conclusions

Keratoconus progression and relapse has been suggested to have an association with sex hormone changes. We report a case of keratoconus progression following gender-affirming hormone therapy in a transgender patient. Our findings continue to support a correlative relationship between sex hormones and corneal ectasia pathophysiology. Further studies are needed to determine causality and to investigate the utility of screening corneal structure prior to the initiation of gender-affirming hormone therapies.

To what extent is pregnancy-induced keratoconus progression reversible? A case-report and literature review

PURPOSE

This report aims to present a case with pregnancy-induced keratoconus (KC) progression and recovery in topographical parameters after a period from delivery/breastfeeding.

METHODS

A 29-year-old woman with bilateral KC experienced progression in maximum keratometry (Kmax; from 47.6 to 48.2 D in the OD and from 53.7 to 55.2 D in the OS) and several Pentacam indices in both eyes.

RESULTS

The Belin ABCD progression score remained unchanged in the right eye (A0B2C0D0) but increased in the left eye (from A2B3C1D1 to A2B4C1D1) (Pentacam HR, Oculus Optikgeräte GmbH, Wetzlar, Germany) during pregnancy/breastfeeding. About 6-months after cessation of breastfeeding, Kmax improved to baseline values in both eyes. Although there were improvements in "A" and "B" scores, final ABCD stage remained higher than the baseline value in the left eye.

CONCLUSIONS

The current report shows asymmetrically bilateral progression of KC during pregnancy and early post-delivery period, which was followed by a partial recovery in Pentacam parameters after discontinuation of breastfeeding. These findings seem to confirm the postulated link between pregnancy and KC progression. On the other hand, in patients with KC, pregnancy-induced corneal alterations might recover after delivery/breastfeeding and clinician should wait for stabilization of corneal parameters to determine treatment strategy.

Corneal characteristics in Down syndrome patients with normal and keratoconic cornea

Purpose

To determine the reference range of corneal indices in Down syndrome patients with normal corneas (DS-N) and to compare it with the corneal indices in Down syndrome patients with keratoconic corneas (DS-KC).

Methods

A study was conducted using the data of 154 eyes of 154 DS-N and 25 eyes of 25 DS-KC patients. Eighteen indices related to thickness, anterior chamber, keratometry, elevation, and aberrations routinely used for KC diagnosis were extracted from the Pentacam.

Results

The mean age of the participants in DS-N and DS-KC groups was 16.73 ± 4.70 and 16.56 ± 4.22 years (P = 0.852). In the DS-N group, 95% CI were 511.65–520.31 for minimum corneal thickness, 2.97–3.07 for anterior chamber depth (ACD), 46.83–47.37 for maximum keratometry (Kmax), 46.13–46.62 for zonal Kmax at 3 mm, 0.35–0.58 for inferior-superior asymmetry (I-S value), 1.56–1.88 for Belin/Ambrósio display-total deviation, 8.65–10.79 for best-fit-sphere posterior elevation at the thinnest point, and 0.18–0.22 for corneal vertical coma. The age-related change in I-S value and corneal spherical aberration (SA) was significant (both P < 0.05). There were significant inter-gender differences in 11 indices; the female DS patients had shallower, steeper, more elevated, and more aberrated corneas (all P < 0.05). There were significant differences in all indices except for ACD (P = 0.372) and corneal SA (P = 0.169) between DS-N and DS-KC groups.

Conclusion

In DS patients aged 10–30 years, the reference ranges of corneal indices are different from the range reported for non-DS subjects and are close to values reported for mild KC non-DS cases. The normal values are different between DS male and female; hence, sex-specific ranges should be considered for diagnosis of corneal abnormality in DS patients.

The Underlying Relationship between Keratoconus and Down Syndrome

Keratoconus (KC) is one of the most significant corneal disorders worldwide, characterized by the progressive thinning and cone-shaped protrusion of the cornea, which can lead to severe visual impairment. The prevalence of KC varies greatly by ethnic groups and geographic regions and has been observed to be higher in recent years. Although studies reveal a possible link between KC and genetics, hormonal disturbances, environmental factors, and specific comorbidities such as Down Syndrome (DS), the exact cause of KC remains unknown. The incidence of KC ranges from 0% to 71% in DS patients, implying that as the worldwide population of DS patients grows, the number of KC patients may continue to rise significantly. As a result, this review aims to shed more light on the underlying relationship between KC and DS by examining the genetics relating to the cornea, central corneal thickness (CCT), and mechanical forces on the cornea, such as vigorous eye rubbing. Furthermore, this review discusses KC diagnostic and treatment strategies that may help detect KC in DS patients, as well as the available DS mouse models that could be used in modeling KC in DS patients. In summary, this review will provide improved clinical knowledge of KC in DS patients and promote additional KC-related research in these patients to enhance their eyesight and provide suitable treatment targets.

Association of keratoconus with serum levels of 25-hydroxyvitamin D and antioxidant trace elements: A systematic review and meta-analysis

The aim of this systematic review and meta-analysis was to summarize and compare the available evidence on the level of vitamin D and antioxidant trace elements between the keratoconus (KC) patients and healthy controls. Seven case-control studies with 830 subjects were found eligible with a systematic search using PubMed, SCOPUS, Web of Science, and EMBASE till November 21, 2021. Data were synthesized with a DerSimonian and Laird random-effects method of meta-analysis. The mean serum vitamin D level was significantly lower in the patients with KC [standardized mean difference (SMD): -0.71; P < 0.001] as compared with the control group. The mean serum vitamin D level decreased more in the progressive patients (SMD: -0.80; P = 0.016) than in the stable patients (SMD: -0.66; P < 0.001) when compared with the control group. The mean serum zinc level was found significantly lower in the patients with KC compared with the control group (SMD: -1.98; P = 0.005). Pooled analysis based on the two studies showed significantly lower mean selenium levels in the KC patients (SMD: -0.34; P = 0.003). Regular evaluation of serum vitamin D, zinc, and selenium levels among the patients with KC at disease onset and future follow-ups could be promising in predicting the progressive disease and disease severity.

Case Report: Bilateral Corneal Ectasia Developed during Pregnancy after Small-incision Lenticule Extraction

SIGNIFICANCE

This case highlights that hormonal changes during pregnancy could affect the biomechanical stability of the cornea and lead to corneal ectasia during pregnancy after corneal refractive surgery.

PURPOSE

We report an unusual case of bilateral corneal ectasia after small-incision lenticule extraction that developed during pregnancy.

CASE REPORT

A 27-year-old woman experienced post-small-incision lenticule extraction corneal ectasia. Her pre-operative corneal topography was normal, with a minimum central corneal thickness of 538 μm in the right eye and 530 μm in the left eye. The manifest refraction was -7.75 -0.25 × 180 and -7.50 -0.75 × 10, and the lenticule thickness was 140 and 139 μm in the right and left eyes, respectively. After 11 months, in her first trimester, the patient began to experience gradually deteriorating blurred vision. Two years post-operatively, corneal ectasia was diagnosed based on topographic data. The automatic optometer examination was -7.25 -2.50 × 42 in the right eye and -11.00 -5.00 × 140 in the left eye. Later, the patient underwent corneal collagen cross-linking to control further progression and was recommended to wear rigid gas-permeable contact lenses.

CONCLUSIONS

Surgeons should be alert for cornea ectasia after refractive surgery in pregnant patients, as hormonal changes during pregnancy may affect corneal biomechanical stability.

Eye diseases during pregnancy: a study with the medical data warehouse in the eye clinic of the Ludwig-Maximilians-Universität München in Munich in Germany

Objective

To analyze the most common ophthalmologic disorders in pregnant women seen in a hospital in Munich in Germany using a big data analysis system, as well as to compare the results obtained with those from other epidemiological studies that used different data acquisition methods.

Methods

We retrospectively analyzed electronic health records of pregnant women who were seen at the ophthalmology department from 2003 to 2019 at the Ludwig-Maximilians-Universität München hospital. The main complaints that led to ophthalmic consultations during this period were evaluated, and also the variation in intraocular pressure of patients throughout gestational trimesters by analyzing data from the data warehouse system.

Results

A total of 27,326 electronic health records were analyzed. Of participants, 149 (0.54%) required eye care during pregnancy. Their mean intraocular pressure was 17mmHg in the first trimester, 12mmHg in the second trimester, and 14mmHg in the third trimester. The most prevalent findings were dry eye (29.3%) and conjunctivitis (16%), and ametropia (16%). The most common posterior segment problem was diabetic retinopathy (4.6%). The lower mean intraocular pressure in the second and third trimester found in our study is in accordance with other studies that used other method for data acquisition.

Conclusion

The most common ophthalmic conditions found in this study population were dry eye, conjunctivitis, and ametropia. The use of data warehouse proved to be useful for acquiring and analyzing data from many patients. This study results are comparable with other studies in published literature that adopted different methodology.

Sex Hormones and Their Effects on Ocular Disorders and Pathophysiology: Current Aspects and Our Experience

Sex hormones are molecules produced by the gonads and to a small extent by the adrenal gland, which not only determine the primary and secondary sexual characteristics of an individual, differentiating man from woman, but also participate in the functioning of the various systems of the body. The evidence that many eye diseases differ in terms of prevalence between men and women has allowed us, in recent years, to carry out several studies that have investigated the association between sex hormones and the pathophysiology of eye tissues. Specific receptors for sex hormones have been found on the lacrimal and meibomian glands, conjunctiva, cornea, lens, retina, and choroid. This work summarizes the current knowledge on the role that sex hormones play in the pathogenesis of the most common ocular disorders and indicates our clinical experience in these situations. The aim is to stimulate an interdisciplinary approach between endocrinology, neurology, molecular biology, and ophthalmology to improve the management of these diseases and to lay the foundations for new therapeutic strategies.

The Role of Estriol and Estrone in Keratoconic Stromal Sex Hormone Receptors

Keratoconus (KC) is a progressive corneal thinning disease that manifests in puberty and worsens during pregnancy. KC onset and progression are attributed to diverse factors that include: environmental, genetics, and hormonal imbalances; however, the pathobiology remains elusive. This study aims to determine the role of corneal stroma sex hormone receptors in KC and their interplay with estrone (E1) and estriol (E3) using our established 3D in vitro model. Healthy cornea stromal cells (HCFs) and KC cornea stromal cells (HKCs), both male and female, were stimulated with various concentrations of E1 and E3. Significant changes were observed between cell types, as well as between males and females in the sex hormone receptors tested; androgen receptor (AR), progesterone receptor (PR), estrogen receptor alpha (ERα), and estrogen receptor beta (ERβ) using Western blot analysis. E1 and E3 stimulations in HCF females showed AR, PR, and ERβ were significantly upregulated compared to HCF males. In contrast, ERα and ERβ had significantly higher expression in HKC's females than HKC's males. Our data suggest that the human cornea is a sex-dependent, hormone-responsive tissue that is significantly influenced by E1 and E3. Therefore, it is plausible that E1, E3, and sex hormone receptors are involved in the KC pathobiology, warranting further investigation.

Sex Hormones, Growth Hormone, and the Cornea

The growth and maintenance of nearly every tissue in the body is influenced by systemic hormones during embryonic development through puberty and into adulthood. Of the ~130 different hormones expressed in the human body, steroid hormones and peptide hormones are highly abundant in circulation and are known to regulate anabolic processes and wound healing in a tissue-dependent manner. Of interest, differential levels of sex hormones have been associated with ocular pathologies, including dry eye disease and keratoconus. In this review, we discuss key studies that have revealed a role for androgens and estrogens in the cornea with focus on ocular surface homeostasis, wound healing, and stromal thickness. We also review studies of human growth hormone and insulin growth factor-1 in influencing ocular growth and epithelial regeneration. While it is unclear if endogenous hormones contribute to differential corneal wound healing in common animal models, the abundance of evidence suggests that systemic hormone levels, as a function of age, should be considered as an experimental variable in studies of corneal health and disease.

Pregnancy and the eye

PURPOSE OF REVIEW

The aim of this study was to summarize common eye changes that may occur during pregnancy, and how pregnancy may affect preexisting eye conditions such as glaucoma and diabetic retinopathy. Challenges and complexities surrounding the treatment of these eye conditions during pregnancy are also highlighted.

RECENT FINDINGS

Refractive changes are common and may persist in the postpartum in patients with keratoconus. Although new medical and surgical glaucoma treatments are available, their safety in pregnancy is unknown. Limited use of topical and systemic glaucoma therapies is recommended, with a preference for selective laser trabeculoplasty as first line treatment in appropriate cases. The impact of pregnancy on diabetic retinopathy remains unclear. Although anti-vascular endothelial growth factor agents are first-line treatment for sight-threatening diabetic retinopathy, their effect on the developing foetus remains unknown and are therefore best avoided in the first and second trimesters. Noninfectious uveitis tends to become less active during pregnancy, allowing the potential tapering of systemic therapy and the use of local topical or injected corticosteroid treatment for active disease as required.

SUMMARY

Significant changes can occur to the eye during pregnancy, wherein the optimal treatment for many ocular conditions remains uncertain, highlighting the need for further research to develop clear recommendations that best balance the need to preserve the mother's sight, and the health of the developing foetus. The need for preconception planning, and collaborative multidisciplinary care between the obstetrician, physician, ophthalmologist and paediatrician is paramount.

Dynamics of keratoconus progression after prior successful accelerated cross-linking treatment during and after pregnancy

PURPOSE

To evaluate the effectiveness of previously applied successful accelerated cross-linking (CXL) treatment in keratoconus stabilization during and after pregnancy.

SETTING

Ankara Yildirim Beyazit University, Ataturk Training and Research Hospital, Turkey.

DESIGN

Prospective, clinical study.

METHODS

Patients who became pregnant with stable keratoconus (after having an accelerated CXL procedure) were included. Uncorrected (UDVA) and corrected distance visual acuity (CDVA), manifest astigmatism (MA), keratometry (K)1, K2, K-max, central corneal thickness (CCT), thinnest corneal thickness (TCT), anterior (AE) and posterior elevation (PE) were recorded at baseline (before CXL), before pregnancy (the last visit after CXL), during pregnancy (3rd trimester) and after pregnancy (the last visit after pregnancy).

RESULTS

Study included 24 eyes of 19 patients. The mean time between CXL and conception was 12.4±5.1 months. The mean post-partum follow-up period was 27.6±13.3 months. The mean UDVA, CDVA, MA, and PE values did not show any significant differences during and after pregnancy compared to the post CXL values (p>0.05). The mean K-max flattened significantly after the CXL procedure (p=0.011), however it increased during pregnancy (p=0.037:after CXL-pregnancy) and then decreased back to the pre-pregnancy level after pregnancy (p=0.035:pregnancy-after pregnancy). The mean K1, K2, AE, CCT, and TCT remained stable during pregnancy and significantly decreased after pregnancy (p<0.05).

CONCLUSION

Keratoconus appears to progress during pregnancy in corneas that have previously received successful accelerated CXL treatment. However, this progress is mostly temporary, and generally regression occurs after delivery.

Benefits of using corneal topography to choose subjective refraction technique in keratoconus (RE-CON): a prospective comparative crossover clinical study

PURPOSE

In prospective no-masking, comparative, crossover monocenter clinical trial, we aimed to evaluate whether the optimal subjective refraction technique varies with the keratoconus topography and to identify relevant topographic criteria.

METHOD

This study included 72 keratoconus eyes with impaired visual acuity. Each eye tested three methods of refraction (Jackson cylinder, astigmatism dial, stenopeic slit), resulting in three eyeglass lenses. Patients were assigned to the group corresponding to the eyeglass lens offering the best visual acuity. Five topographical characteristics were collected via the Pentacam: mean keratometry (Km), maximum keratometry (Kmax), distance from corneal center to Kmax (dKmax), Belin/Ambrosio Display (BAD_D), and index of surface variance (ISV).

RESULTS

Forty-six eyes were included in the dial group (64.8%), 23 eyes in the cylinder group (32.4%), and only 2 eyes in the slit group (2.8%); thus, we only compared dial and cylinder groups. The main analysis retrieved a significant probability to choose dial technic for BAD_D (p = 0.024); when BAD_D is > 9.71 (ROC threshold), the positive predictive value (PPV) = 89.5%, and for ISV, p = 0.012; when ISV is > 77, PPV = 89.1%. The sub-analysis of patients with different visual acuities between cylinder and dial confirmed these results with slightly different thresholds: the probability to choose dial technic was for BAD_D, p = 0.03; when BAD_D is > 7.55, PPV = 90%, and for ISV, p = 0.0084; when ISV is > 71, PPV = 88.5%.

CONCLUSION

Refraction method is linked to topographic indices ISV and BAD_D. A BAD_D > 7.55 indicates the dial method. In addition to keratoconus screening and diagnosis, this study suggests a new application of the topographer to select a suitable refraction method for eyeglass prescription.

TRIAL REGISTRATION

Study registered on the ClinicalTrials.gov database under n°: NCT04174209.

Progressive corneal ectatic disease in pregnancy

Pregnancy influences ocular changes which may exacerbate existing or develop new pathology. This review summarises the existing evidence on the association between pregnancy and progressive keratoconus or iatrogenic keratectasia. Ten online databases were searched systematically. Eligible studies were published in English and reported objective ophthalmic outcomes for women with evidence of (i) a new diagnosis of keratoconus, (ii) keratoconus progression or (iii) iatrogenic keratectasia following refractive surgery; during or within one year of pregnancy. Strength of evidence was assessed using the Oxford Centre for Evidence-Based Medicine levels of evidence. Seventeen articles have reported 33 peripartum women with new-onset or progressive ectasia, evident by signs of corneal hydrops or protrusion (n = 8); steepening on topography imaging (n = 20); a mean decline in best corrected visual acuity by +0.20 logMAR (95% CI -0.01 to +0.40, n = 23); a mean increase in maximum keratometry by 2.18 D (95% CI 1.44 to 2.91, n = 42); a mean decline in spherical equivalent refraction by -1.33 D (95% CI -1.73 to -0.93, n = 41); and a mean increase in astigmatism by -1.61 D (95% CI -2.46 to -0.75, n = 19). Pregnancy is associated with progressive ectasia in some women including those with previously stable keratoconus, or a history of laser-assisted in situ keratomileusis surgery or no history of corneal ectasia. This review highlights the heterogeneity in limited existing evidence, the need for a standardised definition of ectasia progression and further prospective studies for clinical guidelines. Closely monitoring women at risk may assist in early intervention with collagen cross-linking and prevent peripartum vision loss.

Prevalence and incidence of keratoconus in Norway: a nationwide register study

PURPOSE

To estimate the national prevalence and incidence of keratoconus in Norway.

METHODS

In this epidemiologic study, data were obtained from the Norwegian Patient Registry, which provides information from all publicly funded specialist care in Norway. Prevalence of keratoconus was estimated from the total number of patients registered with this diagnosis and incidence from the annual frequency of first-time registrations of patients up to 40 years of age in the period 2010-2018. Data on age and gender of the keratoconus patients were also gathered.

RESULTS

A total of 9832 keratoconus patients were registered. The estimated prevalence in the general population was 192.1 per 100 000 (95% confidence interval (CI): 188.3-195.9), and the estimated annual incidence was 19.8 per 100 000 (95% CI: 18.1-21.5). There was a predominance of males (73%), and mean age for all patients was 37.5 years at first registration in this period.

CONCLUSION

This study reports the frequency of keratoconus from a national patient register during a time period with available modern diagnostic tools. The estimated prevalence and incidence were higher than most previous estimates and show that keratoconus is not a rare condition. As screening was not part of the study, the true prevalence in the general population may be even higher.

Atypical Corneal Ectasia Associated With Vitamin C Deficiency

PURPOSE

To demonstrate a possible correlation between corneal ectasia and vitamin C deficiency.

METHODS

Case series.

RESULTS

This case series covers 3 patients with atypical features of corneal ectasia. All 3 had a peculiar general history and visited our tertiary ophthalmology department complaining about decreased visual acuity. Corneal tomography by Scheimpflug imaging (Pentacam) indicated an irregular astigmatism congruent with a corneal ectasia. A blood test diagnosed vitamin C deficiency.

CONCLUSIONS

To the best of our knowledge, this is the first time a possible correlation between corneal ectasia and vitamin C deficiency is established. Although more research is of course of the essence, it proves useful to determine vitamin C plasma levels in patients presenting with atypical ectasia. To the extent that vitamin C deficiency is indeed diagnosed, it should be substituted orally.

Effect of prolactin on normal and keratoconus human corneal stromal fibroblasts in vitro

Purpose

To examine the effect of prolactin (PRL) on human corneal stromal fibroblasts (CSFs), derived from healthy individuals and from keratoconus (KC) patients, in vitro, specifically assessing physiological and elevated PRL concentrations as apparent during pregnancy.

Methods

Eye bank corneas of 3 female and 3 male healthy individuals as well as the corneal buttons of 3 female and 3 male KC patients were utilized for this study. The endothelium of the cornea was removed with sterile surgical scalpels, the probes were washed repeatedly with Dulbecco’s PBS and corneoscleral rims were trimmed off. Subsequently the corneal stroma was digested with collagenase type I and the harvested CSFs were cultured. We then examined (1) cell proliferation, (2) cell viability and (3) cytokine release of CSFs upon exposure to prolactin in vitro.

Results

With respect to viability and proliferation our experiments did not show significant differences between CSFs exposed to different PRL concentrations. Our data show a significantly lower IL-8 concentration in normal CSFs exposed to 10ng/ml PRL compared to 0ng/ml and 1000ng/ml at 5 hours post exposition. Moreover, we can report significantly lower secretion of IL-8, IL-6, HGF, VEGF and FGFb in KC CSFs compared to normal CSFs, independent of PRL exposure, as determined by cytokine ELISA.

Conclusion

Our data in part points towards corneal cytokine secretion as a possible link between altered stromal PRL concentrations and KC progression. However, in our small dataset a significant influence of PRL concentration on cytokine secretion can only be described for IL-8 in normal CSFs. Further our results contribute to existing reports on the importance of cytokines in KC development, with an emphasis on significantly lower cytokine secretion in KC CSFs compared to normal controls.

Baseline Findings in the Retrospective Digital Computer Analysis of Keratoconus Evolution (REDCAKE) Project

PURPOSE

To present the baseline data for a large cohort of patients with keratoconus enrolled in the Retrospective Digital Computer Analysis of Keratoconus Evolution (REDCAKE) study.

METHODS

Eight centers contributed the Scheimpflug tomographical data for 906 patients with keratoconus, 743 measured with a Pentacam and 163 with a Galilei. The stage of keratoconus at baseline, the location of the reference points, minimum pachymetry (Pmin), and maximum keratometry (Kmax) were analyzed. The intereye asymmetry was evaluated for Kmax (anterior and posterior), Pmin, and keratoconus stage. Average maps and elevation profiles were calculated for each degree of keratoconus.

RESULTS

Keratoconus was more frequently diagnosed in men (73%) than in women (27%). At baseline, 500/1155 eyes (43%) presented with moderate to severe changes in the posterior surface, whereas moderate/severe changes were only found in 252 and 63 eyes when evaluating anterior surface and pachymetry, respectively. The location of Pmin was usually inferotemporal (94% OD and 94% OS), while the location of Kmax showed more variability and significantly higher distance from apex (P < 0.05). The keratoconus presentation was chiefly asymmetric for all the parameters studied. Clear differences between stages could be identified in the maps and elevation profiles.

CONCLUSIONS

The staging map set presented can be used as a graphical guidance to classify keratoconus stage. Keratoconus presented asymmetrically, and generally the posterior surface was more affected than the anterior surface or the thickness. Asymmetry is playing a role in KC detection. Although Pmin was almost invariably located inferotemporally, Kmax location showed higher variability and distance from the apex.

The Enigma of Environmental Factors in Keratoconus

Keratoconus is an ectatic disorder with highly complex and varied causes including genetic variations and environmental factors. Its prevalence varies widely between regions and countries. Many environmental factors have been proposed to be associated with keratoconus, but the interpretation of their individual contributions is difficult due to the presence of many confounding variables. The current literature was reviewed to evaluate the strength of the associations and the causative effects of environmental factors on keratoconus. Ethnicity and consanguinity have been revealed as important determinants for geographical variations in keratoconus prevalence. Eye rubbing, atopy, floppy eyelid syndrome, contact lens wear, pregnancy, and thyroid hormone disturbances are likely associated with keratoconus. The first 4 factors can induce ocular surface inflammation, matrix metalloproteinase release, and keratocyte apoptosis, consistent with the postulated etiology of keratoconus. The associations of keratoconus with UV exposure, cigarette smoking, personality, and sex were less convincing once confounding factors were considered. Future studies powered for multivariate analysis of factors discussed will hopefully shed light on what is truly important in the development and progression of keratoconus.

Topical Estrogen Therapy for Hyperopia Correction in Vivo

Purpose

In vitro studies found that 17β-estradiol (estrogen) modulates corneal biomechanical properties and reduces tissue stiffness. Therefore we hypothesized that topical estrogen might affect the refractive properties of the cornea, inducing a myopic shift.

Methods

Twelve female New Zealand white rabbits 16 weeks old were used. The rabbits were randomly divided to either the treatment group receiving 1.5% (w/v) estrogen eye drops or a control group receiving vehicle only (n = 6 each group). Both groups were given drops (50 µL) to the right eye every 12 hours for 35 days. Ocular examination, pachymetry, intraocular pressure (IOP), keratometry, and refraction were evaluated at baseline and on a weekly basis.

Results

No significant differences were observed between the two groups at baseline in all outcome measures. Both groups displayed corneal flattening and a hyperopic shift. However, the change rate was slower in the treatment group. Repeated measurements analysis revealed a statistically significant difference in keratometry readings between groups (P = 0.034) with steeper keratometry by up to 0.6 diopters in the treatment group. The difference between the two groups diminished and became statistically insignificant after treatment cessation. No significant changes were observed in IOP and pachymetry throughout the study period. No side effects were observed in either group.

Conclusions

Estrogen eye drops induced a myopic shift in keratometry readings. These results suggest that corneal refractive power might be manipulated pharmacologically. Further studies on the physiology behind this change are warranted to facilitate a pathway for development of novel pharmacologic treatments to correct refractive errors.

The keratoconus enigma: A review with emphasis on pathogenesis

PURPOSE

To review the literature on the etiopathogenesis of keratoconus (KC).

METHODS

A literature search was conducted using PUBMED and Google Scholar for keratoconus. The authors analyzed epidemiology studies, reviews, and case reports.

RESULTS

Atopy and ocular surface inflammation are a common features of KC and should lead to a reconsideration of the traditional definition of KC as a "non inflammatory" condition. Co-morbidities suggest that KC may be the ocular manifestation of a systemic disease. Finally, KC shows higher prevalence in certain ethnicities, which calls into question the status of KC as a rare disease, at least in these communities.

CONCLUSION

We believe that future studies should test whether selected, high prevalence populations exhibit specific genetic background and/or ethno-specific environmental risk factors.

Clinical Evaluation and Validation of the Dutch Crosslinking for Keratoconus Score

Importance

Defining keratoconus progression is fundamental in clinical decision making because crosslinking treatments are indicated when the disease is considered progressive. Currently, there is no consensus which parameters should be used to define progression.

Objective

To assess and validate a novel clinical scoring system as an easy-to-use assessment tool for crosslinking treatment in patients with keratoconus.

Design, Setting, and Participants

Prospective cohort study at 2 academic treatment centers. Patients with keratoconus referred between January 1, 2012, and June 30, 2014, with 2-year follow-up were included. Analysis began March 2017.

Interventions

The Dutch Crosslinking for Keratoconus (DUCK) score is based on changes in 5 clinical parameters that are routinely assessed: age, visual acuity, refraction error, keratometry, and subjective patient experience. The DUCK score is derived by scoring 0 to 2 points per item, and cutoffs were determined by clinical experience. We compared the DUCK scores to the conventional 1.0-diopter increase in maximum keratometry criterion, within the last 12 months, in a longitudinal discovery and a validation cohort. Sensitivity analyses and intraitem correlations were performed.

Main Outcomes and Measures

Overall treatment rate reduction and the duly withheld treatment rate.

Results

A total of 504 eyes of 388 patients were available for analysis on disease progression in the course of 12 and 24 months. Baseline patient characteristics of the discovery cohort and the validation cohort were comparable in terms of age (mean [SD], 26.8 [8.3] years vs 26.3 [9.1]), sex (216 of 332 [65%] vs 123 of 172 [72%] men), and maximum keratometry (mean [SD], 53.5 [7.1] vs 52.7 [6.3]). Adhering to the DUCK score, rather than maximum keratometry, was associated with a reduction in overall treatment rate by 23% (95% CI, 18%-30%), without increasing the risk of disease progression (ie, the rate of progression for both groups was equal; ±0%). The DUCK score appears to better identify eyes that were duly withheld treatment by 35% (95% CI, 22%-49%).

Conclusions and Relevance

These results provide validation of the DUCK score as a tool to determine whether a crosslinking treatment might be warranted. Compared with the conventional maximum keratometry criterion of more than 1.0 diopter, the DUCK score may better select patients who might benefit from crosslinking treatment. Potentially, it may prevent unnecessary treatments, reduce exposure to treatment risks, and improve the cost effectiveness of crosslinking.

Changes in corneal biomechanics during pregnancy in Chinese healthy female

PURPOSE

To evaluate the changes of corneal biomechanics and the intraocular pressure during pregnancy in a Chinese healthy female population.

METHODS

A total of 222 unrelated Chinese females were recruited: 52 non-pregnant, 15 pregnant in the first trimester, 68 pregnant in the second trimester, and 87 pregnant in the third trimester. The intraocular pressure and corneal biomechanical parameters, including corneal-compensated intraocular pressure, Goldmann-correlated intraocular pressure, corneal hysteresis, and corneal resistance factor, were measured by an Ocular Response Analyzer G3. Central corneal thickness was measured by Lenstar (LS900).

RESULTS

Corneal hysteresis and corneal resistance factor were significantly higher in pregnant women at the second and third trimesters. Corneal-compensated intraocular pressure was lower in women at the third trimester of pregnancy (p = 0.023), but the difference became insignificant after adjustment for corneal hysteresis. Central corneal thickness was marginally higher in pregnant women than non-pregnant women (p = 0.032). There was a negative correlation between corneal-compensated intraocular pressure and corneal hysteresis (r = -0.337, p < 0.001) and a positive correlation between central corneal thickness and corneal hysteresis (r = 0.711, p < 0.0001). After adjustment for corneal-compensated intraocular pressure, corneal hysteresis remained significantly higher in the second and third trimesters of pregnant women than non-pregnant women (p = 0.031, p = 0.005).

CONCLUSION

This study revealed a significant increase in corneal hysteresis and corneal resistance factor in the second and third trimesters. The increase of corneal hysteresis was independent of corneal-compensated intraocular pressure, indicating pregnant females have unique characteristics in corneal-compensated intraocular pressure and corneal biomechanical properties that may be related to glaucoma and corneal ectatic diseases in pregnancy.

Correlation Between Anterior Chamber Volume and Corneal Biomechanical Properties in Human Eyes

Purpose: To investigate the correlation between anterior chamber volume (ACV) and corneal biomechanical properties in healthy and primary angle closure (PAC) eyes.

Methods: A total of 79 eyes from 55 participants were enrolled in this study, including 24 eyes from 17 PAC patients and 55 eyes from 38 normal subjects. Anterior chamber volume was detected via swept-source anterior segment optical coherence tomography (OCT), and the cornea biomechanical data were obtained via corneal visualization Scheimpflug technology (Corvis ST). A student's t-test, Chi-square test, Pearson's correlation coefficients, and linear regression were used in the statistical analysis.

Results: Anterior chamber volume was significantly associated with a lower deformation altitude (DA) (p = 0.033), higher stiffness parameter (SP-A1) (p = 0.005), younger age (p = 0.001), and higher biomechanical intraocular pressure (bIOP) (p = 0.001). PAC patients were suspected to have a much shallower anterior chamber than healthy participants. In the PAC group, the mean ACV (p < 0.01), SP-A1 (p < 0.01), and bIOP values (p = 0.01) were significantly reduced as compared to the normal group, and DA values (p = 0.02) and age (p = 0.01) were increased as compared to the normal group.

Conclusions: Bigger ACV was associated with lower DA values and age, as well as higher SP-A1 and bIOP values. Reduced corneal stiffness was more commonly found in the PAC suspects as compared to their normal counterparts, indicating a protective physiological mechanism for people with shallower anterior chambers that protects against potential elevations of IOP.

Comparison of standard and accelerated corneal cross-linking for the treatment of keratoconus: a meta-analysis

PURPOSE

To compare results between standard and accelerated corneal collagen cross-linking (CXL) for the treatment of progressive keratoconus.

METHODS

We performed literature searches in PubMed, Cochrane Library, Web of Science, ISRCTN registry, ClinicalTrials.gov, and EMBASE for studies comparing conventional Dresden (C-CXL) and accelerated CXL (A-CXL). Outcomes were clinical results and changes in corneal properties. Weighted mean differences were used to evaluate the effects.

RESULTS

Here, 22 studies with 1158 eyes (C-CXL: 577 eyes; A-CXL: 581 eyes) were included. At the last follow-up, C-CXL was superior regarding minimum keratometry (p < 0.00001) and demarcation line depth (p < 0.00001), whereas A-CXL should be favoured when considering minimum corneal thickness (p = 0.0005). No differences in uncorrected and corrected distance visual acuity (p = 0.09 and 0.98), spherical equivalent (p = 0.11), spherical and cylindrical error (p = 0.29 and 0.32), maximal and average keratometry (p = 0.05 and 0.65), central corneal thickness (p = 0.15), corneal biomechanical properties (p ≥ 0.21 respectively), time of reepithelialization (p = 0.76), subbasal nerve density (p = 0.69), endothelial cell density (p = 0.30) and morphology (p ≥ 0.40 respectively) were found among both groups.

CONCLUSION

Consideration of less corneal thinning favours A-CXL, whereas the deeper demarcation line and greater changes in minimum keratometric values in C-CXL may indicate a higher treatment efficacy. Altogether, C-CXL, as well as A-CXL, provides successful results in the strengthening of corneal tissue.

Prolactin-Induced Protein is a novel biomarker for Keratoconus

PURPOSE

The purpose of the study was to investigate the role of Prolactin-Induced Protein (PIP) as a predictive biomarker for Keratoconus (KC).

PARTICIPANTS

This study included one hundred and forty-seven patients with KC (105 male, 42 female), and sixty healthy controls (27 male, 33 female).

METHODS

Tears, plasma and saliva samples were collected from all participants. In both KC and healthy groups all collected samples were divided into four age subgroups (15-24y), (25-34y), (35-44y) and (45y and up). Samples were analyzed using western blot (WB) and enzyme-linked immunosorbent assay (ELISA). Areas under the receiver operating characteristic curves (AUROCs) were used to evaluate diagnostic accuracy for distinguishing between KC and healthy eyes.

MAIN OUTCOME MEASURES

Difference in PIP protein levels between patients with KC and healthy controls.

RESULTS

Results showed significant downregulation of PIP expression in all three biological fluids on KC patients when compared to healthy controls, independent of age, sex and severity. Since PIP is a hormonal-regulated protein, we also investigated the expression of major sex hormones. We detected significant upregulation in salivary and plasma Dehydroepiandrosterone sulfate (DHEA-S) levels and significant downregulation of estrone and estriol levels, in KC patients compared to healthy controls, independent of sex, age, and KC severity stage. ROC was used to determine the overall predictive accuracy of this protein in KC. Data showed an area under the curve (AUC) for PIP in tears of 0.937 (95%CI: 0.902-0.971), in plasma of 0.928 (95%CI: 0.890-0.968) and in saliva of 0.929 (95%CI: 0.890-0.968).

CONCLUSIONS

Conclusively, our results show that PIP levels are reduced in all three human biological fluids tested, and may independently or in combination with current imaging techniques aid in screening and diagnosis of KC. Our data revealed that PIP levels can potentially differentiate between disease and healthy cases, and PIP levels are stable in relation to KC severity, sex and age. Moreover, alterations in sex hormone levels in correlation with reduced PIP levels in KC provide an intriguing insight in the underlying KC pathophysiology and highlights the role of PIP as a KC biomarker.

Ocular changes during pregnancy

Purpose

To summarize available literature on physiologic and pathologic ocular changes during pregnancy.

Methods

Narrative review of literature.

Results

Ocular changes occur commonly during pregnancy. Although most of these are benign physiologic responses to the metabolic, hormonal, and immunologic modifications to adopt the gestational product, there is some serious pathology that may develop, exacerbate, or even resolve over the course of pregnancy which requires prompt diagnosis and management. The pathological eye conditions can be classified into preexisting pathologies and emerging ocular diseases. Regardless of the different mechanisms by which these ocular changes occur, the key point is the establishment of an effective perinatal screening program to monitor the new development or successive progression of these ocular abnormalities. Irrespective of the visual health status of the pregnant women, regular perinatal eye examination should be scheduled in order to assure continuous surveillance of healthy eyes. Treatment of pathologic ocular conditions or functionally disturbing benign changes relies on an appropriate patient selection.

Conclusions

Discriminating pathological eye disease from physiologic ocular changes is important in order to establish an individualized treatment or preventive plan and constitutes the mainstay of obstetric ophthalmology. This individualized approach should always weigh the ocular benefits of treatment to the mother against the potential harms to the fetus.

Anterior, posterior and biomechanical parameters of cornea during pregnancy in healthy eyes: a cohort study

BACKGROUND

To investigate the effect of pregnancy on anterior, posterior and biomechanical corneal parameters of healthy eyes.

METHOD

In this prospective cohort study, 70 pregnant participants with clinically healthy eyes underwent corneal topographic imaging evaluation by Pentacam and biomechanical assessment by Ocular Response Analyzer (ORA) before pregnancy, at the third trimester of pregnancy (34th week of pregnancy) and 12 months after delivery. The same number of age-matched non-pregnant females was evaluated at the corresponding appointments as the control group.

RESULTS

Assessment of the tomographic, topographic and ORA measurements before pregnancy, at the third trimester of pregnancy and 12 months post partum revealed no statistically significant changes in anterior and posterior corneal flat, steep and mean keratometry, anterior and posterior elevation measurements, central and thinnest corneal thickness, corneal hysteresis, corneal resistance factor and intraocular pressure measurements (p>0.05, repeated measures analysis of variance (ANOVA)). All of the study parameters returned to their baseline levels 1 year after delivery. The ophthalmic parameters of the non-pregnant group remained significantly unchanged during the study period (p>0.05, all comparisons, repeated measures ANOVA). Moreover, no statistically significant differences were found between pregnant and non-pregnant groups in the second (34th week of pregnancy) and third (post partum) appointments (p>0.05, all comparisons, one-way ANOVA).

CONCLUSION

Our findings may suggest a physiological nature for ocular changes during pregnancy that these changes return to baseline values after delivery. The differences between tomographic, topographic and biomechanical corneal parameters before pregnancy, during pregnancy and post partum were not statistically or clinically significant.

Biomechanical properties of early keratoconus: Suppressed deformation signal wave

PURPOSE

To examine the diagnostic validity of different corneal biomechanical parameters for the detection of early keratoconus METHODS: Sixty-one eyes with a diagnosis of early keratoconus and 61 topographically normal eyes were enrolled in the study. All participants underwent testing with the Ocular Response Analyzer (ORA), and 40 indices from each cornea were included in the analysis.

RESULTS

The mean (standard deviation: SD) of keratometry and central corneal thickness in keratoconic corneas was 46.9 (2.5) diopter (D) and 473 (31) μm, respectively. Of the 40 evaluated indices, 32 showed a significant difference between the two groups using t-test (p<0.05). According to the results of logistic regression, the indices of height from the lowest to the highest point in peak 2 (H2¹) and corneal resistance factor (CRF) with R²=0.79 were the best predictors of early keratoconus (p<0.001). H2¹ ≤190 with a sensitivity and specificity of 87% and 91.8%, respectively, and CRF≤8.6 with sensitivity and specificity of 87% and 85.3%, respectively, yielded an overall diagnostic accuracy of 97.3%.

CONCLUSION

This study results point to the important role of novel waveform-derived indices measured by ORA, along with conventional biomechanical indices, for the early diagnosis of keratoconus. The best predictors of keratoconus in its early stages are H2¹ and CRF which showed very high sensitivity and specificity for the detection of early keratoconus.