Acquired pits of the optic nerve. Increased prevalence in patients with low-tension glaucoma

Successful resolution of serous macular detachment following glaucoma-filtering surgery alone for acquired optic disc pit maculopathy

PURPOSE

To describe a case of acquired glaucomatous optic disc pit-related maculopathy successfully treated with glaucoma filtering surgery alone.

CASE DESCRIPTION

A 67-year-old male was diagnosed with advanced primary open angle glaucoma in both eyes, with a cup: disc ratio of 0.85 in the right eye and 0.95 in the left eye. Visual acuity at presentation was 20/60, and intraocular pressure was 14 mm Hg in the left eye. The fundus of the left eye revealed a serous macular retinal detachment due to an acquired optic disc pit.

RESULTS

The left eye of the patient underwent combined cataract and glaucoma filtering surgery. The serous macular detachment resolved completely 15 months after surgery, with a documented visual acuity of 20/40 and intraocular pressure of 10 mm Hg without the use of additional antiglaucoma medications. There was no recurrence of serous macular detachment even after the two-year follow-up visit.

CONCLUSION

This case demonstrates that controlling intraocular pressure alone resulted in complete resolution of serous macular detachment in acquired optic disc pit maculopathy without the need for pars plana vitrectomy.

Phenotypic expressions of the optic disc in primary open-angle glaucoma

BACKGROUND

Which phenotypes are we able to recognize in the optic nerve of patients with primary open angle glaucoma?

METHODS

Retrospective interventional case series. 885 eyes from 885 patients at an outpatient tertiary care centre who met specified criteria for POAG were included. Disc photographs were classified by three glaucoma specialists into the following phenotypes according to their predominant characteristics: (1) concentric rim thinning, (2) focal rim thinning, (3) acquired pit of the optic nerve (APON), (4) tilted, (5) extensive peripapillary atrophy (PPA), and (6) broad rim thinning. Demographic, medical, and ocular data were collected. Kruskal-Wallis was used as a non-parametric test and pairwise comparison was performed by using Wilcoxon rank sum test corrected.

RESULTS

Phenotypic distribution was as follows: 398(45%) focal thinning, 153(18%) concentric thinning, 153(17%) broad thinning, 109(12%) tilted, 47(5%) extensive PPA and 25(3%) APON. Phenotypic traits of interest included a higher proportion of female patients with the focal thinning phenotype (p = 0.015); myopia (p = 0.000), Asian race (OR: 8.8, p = 0.000), and younger age (p = 0.000) were associated with the tilted phenotype; the concentric thinning patients had thicker RNFL (p = 0.000), higher MD (p = 0.008) and lower PSD (p = 0.043) than broad thinning, despite no difference in disc sizes (p = 0.849). The focal thinning group had a localized VF pattern with high PSD compared to concentric thinning (p = 0.005).

CONCLUSION

We report six phenotypic classifications of POAG patients with demographic and ocular differences between phenotypes. Future refinement of phenotypes should allow enhanced identification of genetic associations and improved individualization of patient care.

Myopia: Histology, clinical features, and potential implications for the etiology of axial elongation

Myopic axial elongation is associated with various non-pathological changes. These include a decrease in photoreceptor cell and retinal pigment epithelium (RPE) cell density and retinal layer thickness, mainly in the retro-equatorial to equatorial regions; choroidal and scleral thinning pronounced at the posterior pole and least marked at the ora serrata; and a shift in Bruch's membrane opening (BMO) occurring in moderately myopic eyes and typically in the temporal/inferior direction. The BMO shift leads to an overhang of Bruch's membrane (BM) into the nasal intrapapillary compartment and BM absence in the temporal region (i.e., parapapillary gamma zone), optic disc ovalization due to shortening of the ophthalmoscopically visible horizontal disc diameter, fovea-optic disc distance elongation, reduction in angle kappa, and straightening/stretching of the papillomacular retinal blood vessels and retinal nerve fibers. Highly myopic eyes additionally show an enlargement of all layers of the optic nerve canal, elongation and thinning of the lamina cribrosa, peripapillary scleral flange (i.e., parapapillary delta zone) and peripapillary choroidal border tissue, and development of circular parapapillary beta, gamma, and delta zone. Pathological features of high myopia include development of macular linear RPE defects (lacquer cracks), which widen to round RPE defects (patchy atrophies) with central BM defects, macular neovascularization, myopic macular retinoschisis, and glaucomatous/glaucoma-like and non-glaucomatous optic neuropathy. BM thickness is unrelated to axial length. Including the change in eye shape from a sphere in emmetropia to a prolate (rotational) ellipsoid in myopia, the features may be explained by a primary BM enlargement in the retro-equatorial/equatorial region leading to axial elongation.

Corneal Biomechanics in Primary Open Angle Glaucoma and Ocular Hypertension: A Systematic Review and Meta-analysis

PRCIS

Normal tension glaucoma patients had softer corneas than normal controls, whereas high-tension glaucoma and ocular hypertension patients had stiffer corneas.

PURPOSE

To comprehensively identify the corneal biomechanical differences of patients with primary open angle glaucoma (POAG) and ocular hypertension (OHT) using the Ocular Response Analyzer or the Corvis ST.

METHODS

The electronic databases PubMed, Embase, and Web of Science were comprehensively searched for studies comparing corneal biomechanical differences between POAG and OHT patients with normal controls by Ocular Response Analyzer or Corvis ST. The weighted mean differences and 95% confidence intervals (CIs) were calculated. Subgroup analyses were performed according to the subtypes of POAG, including high-tension glaucoma (HTG) and normal tension glaucoma (NTG).

RESULTS

Thirty-one case-control studies were ultimately included, with 2462 POAG patients, 345 OHT patients, and 3281 normal controls. The corneal hysteresis (CH), corneal resistance factor (CRF), and highest concavity time (HC-t) were all lower in POAG patients than in normal controls. The CH, time at the second applanation (A2t), HC-t, highest concavity radius (HC-R), and deformation amplitude at the highest concavity (HC-DA) were lower in OHT patients, while the CRF, time at the first applanation (A1t), and stiffness parameter at the first applanation (SP-A1) were greater in OHT patients than in normal controls. The subgroup analyses showed that the CH, A2t, length at the second applanation (A2L), and HC-DA were lower in HTG, and the CH, CRF, A1t, and HC-t were lower in NTG patients than in normal controls.

CONCLUSION

The corneas of NTG patients are more deformable than normal controls, whereas the corneas of HTG and OHT patients are stiffer.

Reversal of a glaucomatous optic disc pit

Purpose

To report a patient in whom a glaucomatous optic disc pit (ODP) disappeared spontaneously.

Observations

A 59-year-old Korean woman presented with primary open-angle glaucoma, an ODP, and deep superior cecocentral scotomas. She was treated with topical ocular hypotensive medications and followed. Twenty-eight months later, the superior cecocentral scotomas were not detectable with repeated visual field testing. With repeated optical coherence tomography (OCT), the ODP was narrower and shallower; partially filled with prelaminar tissue, there was an increase in the minimal rim width. At the final examination, the cecocentral scotomas reappeared, although prelaminar tissue continued to fill the ODP.

Conclusions and importance

ODP can disappear spontaneously in glaucomatous eyes under ocular hypotensive treatment. However, this is not always associated with sustained visual field improvement.

Acquired Optic Pits Associated with Laser-assisted In Situ Keratomileusis: A Case Series

Purpose

To present an association between acquired pits of the optic nerve (APON) and prior laser-assisted in situ keratomileusis (LASIK).

Materials and methods

A retrospective case series of patients with an optic disc pit on clinical exam and a history of LASIK. Spectralis Optical Coherence Tomography images and Humphrey Visual Fields were reviewed from prior visits. Extended-depth optical coherence tomography was performed of the optic nerve head at subsequent visits after patients were identified.

Results

Seven patients, aged 45-73 years, were identified each with unilateral optic disc pits. Optic disc pits were located inferior in six patients and centrally in one patient. All demonstrated thinning on optical coherence tomography and six patients had corresponding visual field defects. Four patients identified these defects after their LASIK procedure while two patients were unaware of their reproducible visual field defects. All patients were treated with drops initially. One patient underwent laser trabeculoplasty, and three underwent a trabeculectomy after demonstrating progression on maximum tolerated medical therapy.

Conclusion

This series describes a possible association between LASIK and APON. Given the similarity and severity of vision loss associated with the optic nerve pits in these patients after LASIK, increased awareness and caution is suggested while considering LASIK in susceptible individuals.

How to cite this article

Smith AK, Bussel I, Ling J, et al. Acquired Optic Pits Associated with Laser-assisted In Situ Keratomileusis: A Case Series. J Curr Glaucoma Pract 2020;14(3):106-108.

Optic nerve head anatomy in myopia and glaucoma, including parapapillary zones alpha, beta, gamma and delta: Histology and clinical features

The optic nerve head can morphologically be differentiated into the optic disc with the lamina cribrosa as its basis, and the parapapillary region with zones alpha (irregular pigmentation due to irregularities of the retinal pigment epithelium (RPE) and peripheral location), beta zone (complete RPE loss while Bruch's membrane (BM) is present), gamma zone (absence of BM), and delta zone (elongated and thinned peripapillary scleral flange) within gamma zone and located at the peripapillary ring. Alpha zone is present in almost all eyes. Beta zone is associated with glaucoma and may develop due to a IOP rise-dependent parapapillary up-piling of RPE. Gamma zone may develop due to a shift of the non-enlarged BM opening (BMO) in moderate myopia, while in highly myopic eyes, the BMO enlarges and a circular gamma zone and delta zone develop. The ophthalmoscopic shape and size of the optic disc is markedly influenced by a myopic shift of BMO, usually into the temporal direction, leading to a BM overhanging into the intrapapillary compartment at the nasal disc border, a secondary lack of BM in the temporal parapapillary region (leading to gamma zone in non-highly myopic eyes), and an ocular optic nerve canal running obliquely from centrally posteriorly to nasally anteriorly. In highly myopic eyes (cut-off for high myopia at approximately -8 diopters or an axial length of 26.5 mm), the optic disc area enlarges, the lamina cribrosa thus enlarges in area and decreases in thickness, and the BMO increases, leading to a circular gamma zone and delta zone in highly myopic eyes.

Advances in myopia research anatomical findings in highly myopic eyes

BACKGROUND

The goal of this review is to summarize structural and anatomical changes associated with high myopia.

MAIN TEXT

Axial elongation in myopic eyes is associated with retinal thinning and a reduced density of retinal pigment epithelium (RPE) cells in the equatorial region. Thickness of the retina and choriocapillaris and RPE cell density in the macula are independent of axial length. Choroidal and scleral thickness decrease with longer axial length in the posterior hemisphere of the eye, most marked at the posterior pole. In any eye region, thickness of Bruch's membrane (BM) is independent of axial length. BM opening, as the inner layer of the optic nerve head layers, is shifted in temporal direction in moderately elongated eyes (axial length <26.5 mm). It leads to an overhanging of BM into the intrapapillary compartment at the nasal optic disc side, and to an absence of BM at the temporal disc border. The lack of BM at the temporal disc side is the histological equivalent of parapapillary gamma zone. Gamma zone is defined as the parapapillary region without BM. In highly myopic eyes (axial length >26.5 mm), BM opening enlarges with longer axial length. It leads to a circular gamma zone. In a parallel manner, the peripapillary scleral flange and the lamina cribrosa get longer and thinner with longer axial length in highly myopic eyes. The elongated peripapillary scleral flange forms the equivalent of parapapillary delta zone, and the elongated lamina cribrosa is the equivalent of the myopic secondary macrodisc. The prevalence of BM defects in the macular region increases with longer axial length in highly myopic eyes. Scleral staphylomas are characterized by marked scleral thinning and spatially correlated BM defects, while thickness and density of the choriocapillaris, RPE and BM do not differ markedly between staphylomatous versus non-staphylomatous eyes in the respective regions.

CONCLUSIONS

High axial myopia is associated with a thinning of the sclera and choroid posteriorly and thinning of the retina and RPE density in the equatorial region, while BM thickness is independent of axial length. The histological changes may point towards BM having a role in the process of axial elongation.

The role of lamina cribrosa tissue stiffness and fibrosis as fundamental biomechanical drivers of pathological glaucoma cupping

The primary biomechanical driver of pathological glaucomatous cupping remains unknown. Finite element modeling indicates that stress and strain play key roles. In this article, primarily a review, we utilize known biomechanical data and currently unpublished results from our lab to propose a three-stage, tissue stiffness-based model to explain glaucomatous cupping occurring at variable levels of translaminar pressure (TLP). In stage 1, a short-term increase in TLP gradient induces a transient increase in lamina cribrosa (LC) strain. Beyond a critical level of strain, the tissue stiffness rises steeply provoking cellular responses via integrin-mediated mechanotransduction. This early mechanoprotective cellular contraction reduces strain, which reduces tissue stiffness by return of the posteriorly deflected LC to baseline. In stage 2 a prolonged period of TLP increase elicits extracellular matrix (ECM) production leading to fibrosis, increasing baseline tissue stiffness and strain and diminishing the contractile ability/ability to return to the baseline LC position. This is supported by our three-dimensional collagen contraction assays, which show significantly reduced capacity to contract in glaucoma compared with normal LC cells. Second, 15% cyclic strain in LC cells over 24 h elicits a typical increase in ECM profibrotic genes in normal LC cells but a highly blunted response in glaucoma LC cells. Stage 3 is characterized by persistent fibrosis causing further stiffening and inducing a feed-forward ECM production cycle. Repeated cycles of increased strain and stiffness with profibrotic ECM deposition prevent optic nerve head (ONH) recoil from the new deflected position. This incremental maladaptive modeling leads to pathological ONH cupping.

Rate of visual field decay in glaucomatous eyes with acquired pits of the optic nerve

BACKGROUND

To evaluate the relationship between the presence of an acquired pit of the optic nerve (APON) and the rate of visual field (VF) decay in primary open-angle glaucoma (POAG).

METHODS

Consecutive patients with POAG were screened for APON by three glaucoma specialists. A control group of POAG eyes without APON were matched with the APON group for factors such as age, gender, baseline intraocular pressure and baseline mean deviation (MD). The pointwise rate of change (PRC) was used for pointwise comparisons between the two groups. MD rate, Visual Field Index (VFI) rate and Glaucoma Rate Index (GRI) were used for global rate comparisons. We compared the proportions of eyes progressing in the groups with event-based guided progression analysis (GPA), MD, VFI and GRI criteria.

RESULTS

Mean (SD) PRC was faster in the APON group -1.00 (±2.57) %/year compared with the control group -0.25 (±2.19) %/year; p<0.001. MD rate (-0.22 (±0.27) dB/year vs 0.03 (±0.41) dB/year; p=0.009), VFI rate (-0.81 (±0.86) %/year vs -0.05 (±1.0) %/year; p=0.04) and GRI (-12.27 (±16.27) vs -3.75 (±10.6); p=0.052) were all faster in the APON group compared with controls. The proportion of progressing eyes with GPA, MD, VFI and GRI was not significantly different between the two groups (p>0.1).

CONCLUSIONS

The presence of APON in patients with POAG is associated with focal, fast rates of VF decay. Identification of patients with APON should alert clinicians to the possibility of a fast rate of functional progression and to consider appropriately aggressive treatment of their glaucoma.

Optic disk pits and optic disk pit maculopathy: A review

Optic disk pit, one of the optic disk cavitary anomalies, is generally congenital and unilateral and occurs equally in males and females. Optic disk pit maculopathy is characterized by intraretinal and subretinal fluid at the macula, causing visual deterioration. The origin of the macular fluid and the mechanism of transition to the subretinal space in optic disk pit maculopathy pathophysiology are not yet fully understood. With the evolution of imaging modalities, especially optic coherence tomography, our knowledge of this disorder continues to increase. Although many different treatments have been tried, there is no consensus on the most effective.

A Phenotype of Primary Open-angle Glaucoma With Systemic Vasospasm

PURPOSE

Primary open-angle glaucoma (POAG) patients constitute a heterogenous group. Identification of phenotypic subtypes among these patients may provide a deeper understanding of the disease and aid associations with genotypes. We describe a phenotype of POAG patients associated with a constellation of systemic disorders; patients with this phenotype seem to be vulnerable to optic nerve damage at low intraocular pressures.

MATERIALS AND METHODS

In this retrospective study, we evaluated the medical records of active Jules Stein Eye Institute glaucoma patients from January 1996 to 2017 and included subjects with POAG, acquired pits of the optic nerve (APON), and at least one of the following: systolic blood pressure persistently ≤100 mm Hg, history of migraine headaches or migraine variant, and the Raynaud syndrome.

RESULTS

Of 87 patients (125 eyes) with APON, 37 patients (55 eyes) met the study criteria. In total, 34 patients were female (92%). The median age at the time of diagnosis was 55 years. Nineteen patients (73%) had low systolic blood pressures, same number had Raynaud syndrome, and 25 (68%) had a history of migraine.

CONCLUSIONS

We describe a POAG subtype with APON and systemic vascular instability, predominantly female in their sixth decade of life who demonstrate progressive glaucomatous visual field damage at low intraocular pressure. We suggest that this clinical picture represents an important phenotype of POAG, and that identification and further study of it will help guide diagnosis and development of individualized treatments.

Focal Lamina Cribrosa Defect in Myopic Eyes With Nonprogressive Glaucomatous Visual Field Defect

PURPOSE

To investigate focal lamina cribrosa (LC) defect that spatially correspond to the nonprogressive glaucomatous visual field defect (VFD) in myopic subjects.

DESIGN

Case-control study.

SUBJECTS

We included 159 myopic eyes with glaucomatous VFD under treatment and followed up for 7 years.

METHODS

Serial enhanced-depth imaging spectral-domain optical coherence tomography B-scans of the optic discs were acquired at the end of the follow-up and reviewed for the LC defect. Nonprogressive VFD was defined as having ≤1 progressing point of Humphrey visual field, with a slope calculated using pointwise linear regression worse than -1.0 dB/year at P < .01. Eyes were classified as having either progressive or nonprogressive VFD, and associating factors were evaluated.

RESULTS

Sixty-four subjects (40.3%) exhibited nonprogressive VFD with mean deviation change -0.06 ± 0.22 dB/year. Multivariate logistic regression analysis revealed that presence of LC defect was significantly associated with nonprogressive VFD (odds ratio, 3.96; P = .002). The location of LC defect corresponded spatially to the location of VFD. Nonprogressive eyes with LC defect exhibited lower baseline intraocular pressure (IOP) (16.6 mm Hg vs 21.0 mm Hg, P = .0030) and smaller percentage of IOP change (12.9% vs 30.5%, P < .0001) than those without LC defect, but greater myopic optic disc deformation (10.1 degrees vs 1.2 degrees in torsion angle, P < .0001). When the eyes with LC defect had higher baseline IOP, they exhibited progressive VFD.

CONCLUSIONS

In myopic eyes, there are specific patters of LC defect that are suggested to be associated with nonprogressive glaucomatous VFD.

Congenital anomalies of the optic disc: insights from optical coherence tomography imaging

PURPOSE OF REVIEW

Congenital anomalies of the optic nerve are rare but significant causes of visual dysfunction in children and adults. Accurate diagnosis is dependent on a thorough funduscopic examination, but can be enhanced by imaging information garnered from optical coherence tomography (OCT). We review common congenital optic nerve anomalies, including optic disc pit, optic nerve coloboma, morning glory disc anomaly, and hypoplasia of the optic nerve, review their systemic associations, and discuss insights from OCT imaging.

RECENT FINDINGS

Optic disc pits are a result of a defect in the lamina cribrosa and abnormal vitreomacular adhesions have been shown to cause maculopathy. In patients with optic nerve colobomas, OCT can be instrumental in diagnosing choroidal neovascularization, a rare but visually devastating complication. The pathogenesis of morning glory disc anomaly has been more clearly elucidated by OCT as occurring from a secondary postnatal mesenchymal abnormality rather than only the initial neuroectodermal dysgenesis of the terminal optic stalk in isolation. OCT studies of optic nerve hypoplasia have demonstrated significant thinning of the inner and outer retinal layers of the perifoveal region and thicker layers in the fovea itself, resulting in a foveal hypoplasia-like pathology, that is, significantly correlated to poorer visual outcomes.

SUMMARY

OCT provides detailed in-vivo analysis of these anatomic anomalies and their resulting pathologies, shedding new insights on the pathogenesis, diagnosis, and potential visual outcomes of these conditions in children. Further study employing OCT to elucidate structure-function relationships of congenital optic nerve anomalies will help expand the role of OCT in clinical practice related to diagnosis, prognosis, and management of these entities.

Progressive Retinal Nerve Fiber Layer Atrophy Associated With Enlarging Peripapillary Pit

PURPOSE

To report a case in which progressive retinal nerve fiber layer (RNFL) atrophy was observed along with enlargement of the peripapillary pit.

PATIENTS AND METHODS

A 34-year-old male was diagnosed with primary open-angle glaucoma and followed up for 4 years with regular ophthalmic examinations. Both eyes were myopic (-10 D, OD and -10.5 D, OS), and untreated intraocular pressures were 18 mm Hg (OD) and 16 mm Hg (OS).

RESULTS

A subtle depression of the superotemporal peripapillary area was deepened and emerged as a peripapillary pit during the follow-up period. With the enlargement of the peripapillary pit, a RNFL defect at the location of pit widened and thinned continuously. The enlargement of the pit was documented by the spectral-domain optical coherence tomography posterior pole scanning.

CONCLUSIONS

Progressive RNFL atrophy was observed with enlargement of the peripapillary pit. The finding suggests that tensile stress derived from the scleral stretching may have significant influence on the integrity of the RNFL.

Update on Normal Tension Glaucoma

Normal tension glaucoma (NTG) is labelled when typical glaucomatous disc changes, visual field defects and open anterior chamber angles are associated with intraocular pressure (IOP) constantly below 21 mmHg. Chronic low vascular perfusion, Raynaud's phenomenon, migraine, nocturnal systemic hypotension and over-treated systemic hypertension are the main causes of normal tension glaucoma. Goldmann applanation tonometry, gonioscopy, slit lamp biomicroscopy, optical coherence tomography and visual field analysis are the main tools of investigation for the diagnosis of NTG. Management follows the same principles of treatment for other chronic glaucomas: To reduce IOP by a substantial amount, sufficient to prevent disabling visual loss. Treatment is generally aimed to lower IOP by 30% from pre-existing levels to 12-14 mmHg. Betaxolol, brimonidine, prostaglandin analogues, trabeculectomy (in refractory cases), systemic calcium channel blockers (such as nifedipine) and 24-hour monitoring of blood pressure are considered in the management of NTG. The present review summarises risk factors, causes, pathogenesis, diagnosis and management of NTG.

Review of external ocular compression: clinical applications of the ocular pressure estimator

PURPOSE

The authors have previously validated an Ocular Pressure Estimator (OPE) that can estimate the intraocular pressure (IOP) during external ocular compression (EOC). The authors now apply the OPE in clinical states where EOC is clinically important. The original work is described for two periods of risk: during sleep and during the digital ocular massage (DOM) maneuver used by surgeons after trabeculectomy to keep the operation functional. Other periods of risk for external ocular compression are then reviewed.

METHODS

The first protocol estimated the IOP in the dependent eye during simulated sleep. Subjects had their IOPs initially measured in an upright-seated position, immediately upon assuming a right eye dependent side sleeping position (with nothing contacting the eye), and then 5 minutes later while still in this position. While maintaining this position, the fluid filled bladder of the OPE was then placed between the subject's closed eye and a pillow during simulated sleep. The IOP was continuously estimated in this position for 5 minutes. The subjects then had the IOP measured in both eyes in an upright-seated position. The second protocol determined if a larger vertical cup-to-disc ratio was more common on the side that patients reported they preferred to sleep on. The hypothesis was that chronic asymmetric, compression induced, elevations of IOP during sleep would be associated with otherwise unexplained asymmetry of the vertical cup-to-disc ratio. The third protocol assessed the IOP during DOM. The OPE was used to characterize the IOP produced during the DOM maneuver of five glaucoma surgeons. After this, 90 mmHg was chosen as a target pressure for DOM. The surgeons were then verbally coached during three additional compressions. After a 5-minute period, the surgeons were asked to reproduce this targeted IOP during subsequent compressions.

RESULTS

The mean IOP during the "sleep session" was 22±5 mmHg (SEM). The mean peak pressure was 40±11 mmHg (SEM) and the mean trough pressure was 15±2 mmHg (SEM). There was a 78% agreement between the eye that was reported to be dependent during sleep and the eye with the larger vertical cup-to-disc ratio, for eyes with at least a 0.10 cup-to-disc ratio difference, P=0.001, n=137. The OPE estimated an average induced IOP during typical DOM of 104±8 mmHg (SEM), with each compression having an average range of 17±3 mmHg (SEM). After coaching, and a 5-minute waiting period, the average induced IOP reduced to 95±3 mmHg (SEM) with a reduced average range of IOP to 11±1 mmHg.

CONCLUSION

The OPE was successfully used to estimate the IOP while subjects experienced EOC during normal sleep postures. These EOC-induced elevations of IOP were considerable, and likely contribute to significant ocular pathology, not only for glaucoma, but for retinal vascular occlusive diseases, retinal vascular leakage, and the induction of the ocular-cardiac reflex in infants, as well. The correlation of a larger vertical cup-to-disc ratio in patients with a sleep posture preference suggests a causal relationship, since patients with other conditions known to be associated with cup-to disc ratio asymmetry were excluded from this study. The OPE is a useful device to teach DOM to surgeons and patients for home use.

New directions in the treatment of normal tension glaucoma

Glaucoma is a progressive optic neuropathy that causes characteristic changes of the optic nerve and visual field in relation to intraocular pressure (IOP). It is now known that glaucoma can occur at statistically normal IOPs and prevalence studies have shown that normal tension glaucoma (NTG) is more common than previously thought. While IOP is believed to be the predominant risk factor in primary open angle glaucoma (POAG), IOP-independent risk factors, such as vascular dysregulation, are believed to play an important part in the pathogenesis of NTG. Though certain distinguishing phenotypic features of NTG have been reported, such as an increased frequency of disc hemorrhages, acquired pits of the optic nerve and characteristic patterns of disc cupping and visual field loss, there is much overlap of the clinical findings in NTG with POAG, suggesting that NTG is likely part of a continuum of open angle glaucomas. However, IOP modification is still the mainstay of treatment in NTG. As in traditional POAG, reduction of IOP can be achieved with the use of medications, laser trabeculoplasty or surgery. Studies now show that the choice of medication may also be important in determining the outcomes of these patients. Though it is likely that future treatment of NTG will involve modification of both IOP and IOP-independent risk factors, current efforts to develop IOP-independent neuroprotective treatments have not yet proven to be effective in humans.

Cerebrospinal fluid pressure in the pathogenesis of glaucoma

The optic nerve head forms the interface between the intraocular compartment and the retrobulbar compartment. The former is characterized by what we term intraocular pressure (IOP) and the latter by orbital cerebrospinal fluid pressure (CSFP). The trans-lamina cribrosa pressure difference (TLCPD) is defined as the difference between the pressures in the two compartments. Any change in one of them can be associated with a disturbance of homeostasis of the optic nerve head, such as papilledema or glaucomatous optic neuropathy. In particular, glaucomatous optic neuropathy may be due to either an elevated IOP and/or an abnormally low orbital CSFP, or due to a change in the time-dependent relationship between the pulse-synchronous changes in IOP and orbital CSFP. Based on the triangular relationships between IOP, CSFP, and blood pressure, glaucoma may be described as an imbalance between these three pressure parameters, eventually leading to an increased TLCPD. Because the retinal and choroidal venous blood drains through the CSFP space, elevated CSFP may be associated with dilated retinal veins, increased incidence of retinal vein occlusions, higher prevalence and severity of diabetic retinopathy, and thicker choroid.

Laser treatment of macular retinoschisis due to acquired optic nerve pit from glaucoma

Macular retinoschisis can be caused by acquired optic nerve pit from glaucoma. This study evaluated the efficacy of laser treatment for this disorder. We report on five eyes from three patients with macular retinoschisis and a history of glaucoma. Spectral domain optical coherence tomography was used for diagnosis and follow-up. Treatment was performed with barrier laser on the temporal margin of the optic nerve. Following treatment, patients' average vision improved by 1 line on the Snellen chart at average follow-up of 12.3 months. All five eyes showed significant improvement in macular retinoschisis. The tracts connecting the optic pit to the retinoschisis completely closed in three eyes and nearly closed in two eyes. These cases demonstrate that laser photocoagulation is an effective treatment of macular retinoschisis from acquired optic nerve pit. It can serve as first-line treatment before more invasive options such as vitrectomy are considered.

Emerging risk factors for glaucoma onset and progression

Glaucoma is a complex, multifactorial neurodegenerative disease process that leads to progressive damage to the optic nerve and irreversible visual impairment. Identification of ocular and systemic risk factors for disease onset and progression is critical for disease detection and surveillance. Although a great deal is known about risk factors for glaucoma, our expanding knowledge of glaucoma genotypes and phenotypes combined with advancements in technology and understanding of disease progression is rapidly enhancing our understanding of who is at greatest risk for glaucomatous visual impairment.

Microstructure of the optic disc pit in open-angle glaucoma

PURPOSE

To investigate the structural and clinical characteristics of the optic disc pit (ODP) in primary open-angle glaucoma (POAG) via enhanced depth imaging (EDI) spectral-domain optical coherence tomography (SD-OCT).

DESIGN

Prospective, observational case series.

PARTICIPANTS

Seventy POAG eyes clinically diagnosed with an ODP via stereo disc photography.

METHODS

Optic discs were scanned using EDI SD-OCT. Serial horizontal and vertical B-scan images covering the optic discs were obtained from each eye. The structural characteristics of the ODP were investigated via 3-dimensional images constructed from the serial B-scans, focusing on the presence of alterations in the contour of the lamina cribrosa (LC) or prelaminar tissue (PLT), in conjunction with associated clinical characteristics.

MAIN OUTCOME MEASURES

The structural characteristics of the ODP and associated clinical characteristics.

RESULTS

In the EDI SD-OCT images, the ODP was viewed as an isolated alteration of the LC (n = 14, 20.0%) or PLT (n = 16, 22.9%) or an alteration of both the LC and PLT (n = 40, 57.1%). Alterations of the LC were located at the mid-periphery near the LC insertion (n = 17) or far periphery adjacent to the LC insertion (n = 37), and the depth of alteration was deep (n = 23), involving nearly full-thickness LC, or shallow (n = 31), with partially visible LC at the base. Fifty-four eyes (77.1%) exhibited parafoveal visual field (VF) defect within 10 degrees of fixation, and in 98.1% of these eyes (53/54) it was spatially associated with the location of ODP. The parafoveal VF defect was more prevalent in eyes with LC alteration than those without (83.3% vs. 56.2%, P = 0.023) and in eyes with deep LC defect than those with shallow defect (95.7% vs. 74.2%, P = 0.036). Disc hemorrhage (32.4% vs. 0.0%, P = 0.008) and peripapillary retinoschisis (18.9 vs. 0.0%, P = 0.055) were more strongly associated with LC alterations located at the far periphery than at the mid-periphery.

CONCLUSIONS

Enhanced depth imaging SD-OCT facilitated visualization of the varied structure of the ODP, which presented as alteration of the LC or PLT or both. The clinical significance of differing characteristics of ODP microstructure remains to be determined.

Bilateral papillomacular retinoschisis and macular detachment accompanied by focal lamina cribrosa defect in glaucomatous eyes

PURPOSE

We report here a patient with bilateral papillomacular retinoschisis with an enlarged glaucomatous optic nerve head cup and a focal lamina cribrosa defect, the findings of our clinical investigations of this case, and the chosen treatment and outcome.

DESIGN

This is an observational case report.

METHODS

Clinical examinations were performed using simultaneous confocal scanning laser ophthalmoscopy and optical coherence tomography (OCT). The patient was treated by pars plana vitrectomy (PPV).

RESULTS

The left eye had a macular detachment with a presumed acquired pit of the optic nerve, while the right eye did not have an obvious optic nerve pit. Enhanced depth imaging OCT showed focal lamina cribrosa defects in both eyes. PPV was performed on the left eye, which resulted in a re-attachment of the macula and improvement of the visual acuity.

CONCLUSIONS

Our findings suggest that the pathological changes were most likely due to focal lamina cribrosa defects in both glaucomatous eyes. This type of maculopathy can be successfully treated with PPV.

Optic Disk Pit and Iridociliary Cyst Precipitating Angle Closure Glaucoma

Primary angle closure glaucoma is usually a bilateral disease, though it may be asymmetrical. However, it is unusual to see advanced glaucoma in one eye and no disk damage in the other. We present a case of unilateral angle closure glaucoma complicated by an optic disk pit and iridociliary cysts.

How to cite this article: Kaushik S, Ichhpujani P, Kaur S, Pandav SS. Optic Disk Pit and Iridociliary Cyst Precipitating Angle Closure Glaucoma. J Current Glau Prac 2014;8(1): 33-35.

Histological changes of high axial myopia

To describe pathological changes in the anatomy of highly myopic (axially elongated) eyes, enucleated globes were examined by light microscopy and ocular structures were measured histomorphometrically. These studies revealed that highly axially myopic eyes show continuous thinning of the sclera starting at or behind the equator with a maximal thinning at the posterior pole; a profound thinning of the choroid decreasing from ∼ 250 to <10 μm in extreme axial myopia, secondary macular defects in the Bruch's membrane associated with a complete loss of retinal pigment epithelium and choriocapillaris, and retinal photoreceptors; a Bruch's membrane of normal thickness in contrast to the profound thinning of the choroid and the sclera; an up to 10-fold elongation and thinning of the peripapillary scleral flange as anterior roof of the orbital cerebrospinal fluid space, and subsequently a retrobulbar extension of the cerebrospinal fluid space; an increased distance of the peripapillary arterial circle of Zinn-Haller to the optic disc border; an elongation and thinning of the lamina cribrosa with a subsequently decreased distance between the intraocular pressure compartment and the retrobulbar orbital cerebrospinal fluid pressure compartment; an increasing exposure of the peripheral posterior lamina cribrosa surface to the cerebrospinal fluid space, no longer buffered by the solid optic nerve tissue; and the development and enlargement of parapapillary gamma zone, in contrast to a myopia-independent parapapillary beta zone. These anatomical changes may be associated with high axial myopia-related complications such as an increased susceptibility of glaucomatous optic neuropathy and myopic retinopathy.

A classic temporal optic disc pit showing progression in the corresponding optic nerve fiber and visual field defects

PURPOSE

We report a rare case with a classic temporal optic disc pit (ODP) showing the progression of an associated nerve fiber layer defect (NFLD) with the corresponding visual field defect (VFD).

METHODS

We describe the patient's medical records and review the pertinent literature.

RESULTS

A 54-year-old woman had a temporal ODP, which was considered to be congenital, associated with both NFLD expanded to both the upper and lower sides of the horizontal line and corresponding VFD and a small ODP-like excavation at the 6.5 o'clock position on the disc edge with a narrow NFLD OD. During the 5-year follow-up period, both the NFLD and VFD associated with the temporal pit progressed without serous retinal detachment. The small ODP-like excavation located at the 6.5 o'clock position also showed progressive NFLD in the temporal lower quadrant with advanced VFD, which suggested that the excavation might be associated with glaucoma.

CONCLUSION

Based on the observation that the VFD occupied the two temporal quadrants with no step, an NFLD with corresponding VFD associated with a classic temporal ODP, although not considered to be related to glaucoma, can progress.

Double-vitrectomy for optic disc pit maculopathy

BACKGROUND

The origin of the fluid and precise pathophysiology of optic pit maculopathy remain unclear. It has been suggested that submacular fluid originates either from vitreous or cerebrospinal fluid. We report a case of optic pit maculopathy which was unsuccessfully treated with vitrectomy and internal limiting membrane (ILM) peeling, and subsequently resolved with revision of vitrectomy and gas tamponade.

METHODS

We report a case of optic disc pit maculopathy, well documented by spectral- domain optical coherence tomography, before and after pars plana vitrectomy with ILM peeling, and its revision with gas tamponade.

RESULTS

After ILM peeling, there was no improvement either in visual acuity or in the tomographic aspect of the retina. A revision of the surgery was then needed and gas tamponade was performed, which resulted in a complete resolution of the optic pit maculopathy.

CONCLUSION

The absence of improvement after ILM peeling during the first surgical procedure, accompanied by resolution of the clinical picture with gas tamponade during the second surgical procedure, sustained the hypothesis of a subarachnoidal origin of the fluid.

Corneal biomechanical properties in normal-tension glaucoma

PURPOSE

To investigate the intraocular pressure (IOP) and corneal biomechanical properties of normal and normal-tension glaucoma (NTG) eyes.

METHODS

This study included 83 normal and 83 NTG eyes. We measured corneal-compensated IOP (IOPcc), Goldmann-correlated IOP (IOPg), corneal resistance factor (CRF), corneal hysteresis (CH) and central corneal thickness (CCT) three times each for normal and NTG eyes using an Ocular Response Analyzer (ORA).

RESULTS

No significant difference in CCT was seen between normal eyes (541.4 ± 26.8 μm) and NTG eyes (535.4 ± 24.9 μm; p = 0.16). IOPcc was significantly higher in NTG eyes (16.1 ± 2.6 mmHg) than in normal eyes (15.1 ± 2.9 mmHg; p = 0.01), while IOPg was significantly lower in NTG eyes (14.1 ± 2.7 mmHg) than in normal eyes (15.1 ± 3.0 mmHg; p = 0.04). CRF and CH were significantly lower in NTG eyes (CRF, 8.9 ± 1.5 mmHg; CH, 9.2 ± 1.3 mmHg) than in normal eyes (CRF, 10.6 ± 1.4 mmHg; CH, 10.8 ± 1.3 mmHg; p < 0.0001 each).

CONCLUSION

IOPcc was significantly higher in NTG eyes than in normal eyes. The ORA may be useful for distinguishing between the IOPcc of NTG eyes with normal IOP and that of normal eyes. In addition, the ORA enables CRF and CH to be measured in vivo, and weakness of the lamina cribrosa may be clinically inferred from the fact that CRF and CH were reduced in NTG eyes in our study. Low CRF and CH may be clues to the pathology of NTG.

Optic disc pit with peripapillary retinoschisis presenting as a localized retinal nerve fiber layer defect

A 59-year-old woman was referred to our clinic for a glaucoma evaluation. The visual acuity and intraocular pressure were normal in both eyes. However, red-free fundus photography in the left eye showed a superotemporal wedge-shaped retinal nerve fiber layer defect, and visual field testing showed a corresponding partial arcuate scotoma. In an optical coherence tomography examination, the macula was flat, but an arcuate-shaped peripapillary retinoschisis was found. Further, the retinoschisis seemed to be connected with a superotemporal optic pit shown in a disc photograph. After 3 months of a topical prostaglandin analogue medication, the intraocular pressure in the retinoschisis eye was lowered from 14 to 10 mmHg and the peripapillary retinoschisis was almost resolved. We report a rare case of an optic disc pit with peripapillary retinoschisis presenting as a localized retinal nerve fiber layer defect.

Role of cerebrospinal fluid pressure in the pathogenesis of glaucoma

The pathogenesis of normal (intraocular) pressure glaucoma has remained unclear so far. As hospital-based studies showed an association of normal-pressure glaucoma with low systemic blood pressure, particularly at night, and with vasospastic symptoms, it has been hypothesized that a vascular factor may play a primary role in the pathogenesis of normal-pressure glaucoma. That assumption may, however, be contradicted by the morphology of the optic nerve head. Eyes with normal-pressure glaucoma and glaucomatous eyes with high-intraocular pressure can show a strikingly similar appearance of the optic nerve head, including a loss of neuroretinal rim, a deepening of the optic cup, and an enlargement of parapapillary atrophy. These features, however, are not found in any (other) vascular optic neuropathy, with the exception of an enlargement and deepening of the optic cup in arteritic anterior ischaemic optic neuropathy. One may additionally take into account (i) that it is the trans-lamina cribrosa pressure difference (and not the trans-corneal pressure difference, i.e. the so-called intraocular pressure) which is of importance for the physiology and pathophysiology of the optic nerve head; (ii) that studies have shown that the anatomy of the optic nerve head including the intraocular pressure, the anatomy and biomechanics of the lamina cribrosa and peripapillary sclera, retrobulbar orbital cerebrospinal fluid pressure and the retrobulbar optic nerve tissue pressure may be of importance for the pathogenesis of the highly myopic type of chronic open-angle glaucoma; (iii) that studies have suggested a physiological association between the pressure in all three fluid filled compartments, i.e. the systemic arterial blood pressure, the cerebrospinal fluid pressure and the intraocular pressure; (iv) that an experimental investigation suggested that a low cerebrospinal fluid pressure may play a role in the pathogenesis of normal (intraocular) pressure glaucoma; and (v) that recent clinical studies reported that patients with normal (intraocular) pressure glaucoma had significantly lower cerebrospinal fluid pressure and a higher trans-lamina cribrosa pressure difference when compared to normal subjects. One may, therefore, postulate that a low cerebrospinal fluid pressure may be associated with normal (intraocular) pressure glaucoma. A low systemic blood pressure, particularly at night, could physiologically be associated with a low cerebrospinal fluid pressure, which leads to an abnormally high trans-lamina cribrosa pressure difference and as such to a similar situation as if the cerebrospinal fluid pressure is normal and the intraocular pressure is elevated. This model could explain why patients with normal (intraocular) pressure glaucoma tend to have a low systemic blood pressure, and why eyes with normal (intraocular) pressure glaucoma and eyes with high-pressure glaucoma, in contrast to eyes with a direct vascular optic neuropathy, show profound similarities in the appearance of the optic nerve head.

Normal-tension glaucoma (Low-tension glaucoma)

Glaucoma is now considered an abnormal physiology in the optic nerve head that interacts with the level of intraocular pressure (IOP), with the degree and rate of damage depending on the IOP and presumably the degree of abnormal physiology. Diagnosis of normal-tension glaucoma (NTG), defined as glaucoma without a clearly abnormal IOP, depends on recognizing symptoms and signs associated with optic nerve vulnerability, in addition to absence of other explanations for disc abnormality and visual field loss. Among the findings are a halo or crescent of absence of retinal pigment epithelium around the disc, bilateral pre-chiasmal visual field defects, splinter hemorrhages at the disc margin, vascular dysregulation (low blood pressure, cold hands and feet, migraine headache with aura, and the like), or a family history of glaucoma. Possibly relevant, is a history of hemodynamic crisis, arterial obstructive disease, or sleep apnea. Neurological evaluation with imaging is needed only for atypical cases or ones that progress unexpectedly. Management follows the same principle of other chronic glaucomas, to lower the IOP by a substantial amount, enough to prevent disabling visual loss. However, many NTG cases are non-progressive. Therefore, it may often be wise in mild cases to determine whether the case is progressive and the rate of progression before deciding on how aggressivene to be with therapy. Efforts at neuroprotection and improvement in blood flow have not yet been shown effective.

Normal versus high tension glaucoma: a comparison of functional and structural defects

PURPOSE

To compare visual field defects obtained with both multifocal visual evoked potential (mfVEP) and Humphrey visual field (HVF) techniques to topographic optic disc measurements in patients with normal tension glaucoma (NTG) and high tension glaucoma (HTG).

METHODS

We studied 32 patients with NTG and 32 with HTG. All patients had reliable 24-2 HVFs with a mean deviation of -10 dB or better, a glaucomatous optic disc and an abnormal HVF in at least 1 eye. Multifocal VEPs were obtained from each eye and probability plots created. The mfVEP and HVF probability plots were divided into a central 10-degree radius and an outer arcuate subfield in both superior and inferior hemifields. Cluster analyses and counts of abnormal points were performed in each subfield. Optic disc images were obtained with the Heidelberg Retina Tomograph III. Eleven stereometric parameters were calculated. Moorfields regression analysis and the glaucoma probability score were performed.

RESULTS

There were no significant differences in mean deviation and pattern standard deviation values between NTG and HTG eyes. However, NTG eyes had a higher percentage of abnormal test points and clusters of abnormal points in the central subfields on both mfVEP and HVF than HTG eyes. For Heidelberg Retina Tomograph III, there were no significant differences in the 11 stereometric parameters or in the Moorfields regression analysis and glaucoma probability score analyses of the optic disc images.

CONCLUSIONS

The visual field data suggest more localized and central defects for NTG than HTG.

Bilateral developmental glaucoma associated with optic disc pit and uveal effusion

This report describes the association of developmental glaucoma with bilateral optic disc pits and uveal effusion. A case of developmental glaucoma (isolated trabeculodysgenesis) presented with bilateral optic disc pits and uveal effusion detected on ultrasound biomicroscopy. Uveal effusion and optic disc pits could be associated with bilateral developmental glaucoma. The constellation of symptoms reported here have not been previously described in the literature and thus merit exploration.

Lower corneal hysteresis in glaucoma patients with acquired pit of the optic nerve (APON)

OBJECTIVE

Acquired pit-like changes of the optic nerve head (APON) are characteristic of glaucomatous damage and may be a sign of a localized susceptibility of the optic nerve. Thus, it is possible that biomechanical properties of the ocular tissues may play a pressure-independent role in the pathogenesis of glaucoma. Corneal hysteresis (CH) appears to provide information of the biomechanical properties of the ocular hull tissues. The purpose of this study was to compare CH of patients with primary open angle glaucoma (POAG) with and without APON.

METHODS

A prospective case control study was done. POAG patients with and without APON were measured using the Ocular Response Analyzer by masked investigators. Patients in both groups were matched for sex, age, corneal thickness, and type of glaucoma according to maximal IOP (NTG or POAG). Statistical analysis was done using ANOVA.

RESULTS

Corneal hysteresis of 16 glaucomatous eyes with APON and 32 controls (glaucoma without APON) was measured. The mean (+/-SD) CH in the APON group was 8.89 (+/-1.53) and 10.2 (+/-1.05) in the control group. The difference is statistically significant (p=0.005).

CONCLUSIONS

Corneal hysteresis in POAG patients with APON was significantly lower than in patients that did not have such structural changes of the optic disc. These findings may reflect pressure-independent mechanisms involved in the pathogenesis of such glaucomatous optic nerve changes.

Gene therapy and transplantation in CNS repair: The visual system

Normal visual function in humans is compromised by a range of inherited and acquired degenerative conditions, many of which affect photoreceptors and/or retinal pigment epithelium. As a consequence the majority of experimental gene- and cell-based therapies are aimed at rescuing or replacing these cells. We provide a brief overview of these studies, but the major focus of this review is on the inner retina, in particular how gene therapy and transplantation can improve the viability and regenerative capacity of retinal ganglion cells (RGCs). Such studies are relevant to the development of new treatments for ocular conditions that cause RGC loss or dysfunction, for example glaucoma, diabetes, ischaemia, and various inflammatory and neurodegenerative diseases. However, RGCs and associated central visual pathways also serve as an excellent experimental model of the adult central nervous system (CNS) in which it is possible to study the molecular and cellular mechanisms associated with neuroprotection and axonal regeneration after neurotrauma. In this review we present the current state of knowledge pertaining to RGC responses to injury, neurotrophic and gene therapy strategies aimed at promoting RGC survival, and how best to promote the regeneration of RGC axons after optic nerve or optic tract injury. We also describe transplantation methods being used in attempts to replace lost RGCs or encourage the regrowth of RGC axons back into visual centres in the brain via peripheral nerve bridges. Cooperative approaches including novel combinations of transplantation, gene therapy and pharmacotherapy are discussed. Finally, we consider a number of caveats and future directions, such as problems associated with compensatory sprouting and the reformation of visuotopic maps, the need to develop efficient, regulatable viral vectors, and the need to develop different but sequential strategies that target the cell body and/or the growth cone at appropriate times during the repair process.

Neurosensory Detachment Arising From a Fractured Inner-Limiting Membrane Secondary to Chronically Elevated Intraocular Pressure

Diffuse optic nerve excavation and focal rim loss mimicking an optic pit have never been reported to predispose patients to serous detachments despite their relative frequency among patients with glaucoma. Recent reports of idiopathic macular schisis detachments occurring in the setting of elevated intraocular pressure without evidence of a contributing comorbidity have caused some to speculate that alternative mechanisms exist with the capacity to engender these retinal complications. Experimental simian research has unveiled the capacity of chronically elevated intraocular pressure to yield conduction portals between the posterior hyaloid face and the subretinal space by inducing microscopic fractures in the inner-limiting membrane. To our knowledge, this is the first case report providing objective evidence of an idiopathic neurosensory detachment resulting from a fractured inner-limiting membrane arising in the setting of chronically elevated intraocular pressures.

CASE REPORT

A 34-year old black man presented with transient eye pain and fluctuating vision in his left eye with his current spectacle prescription. A 2-year history of right eye blindness from glaucoma was uncovered. Funduscopic evaluation revealed a broad neurosensory detachment in the setting of an excavated optic nerve in the patient's right eye. Optical coherence tomography confirmed the hydrodynamic separation of the sensory retina from the retinal pigmented epithelium and permitted visualization of a fractured inner-limiting membrane with a contiguous communication between the posterior hyaloid face and the subretinal space at the nasal limit of the detachment. Fluorescein angiography studies identified the absence of chorioretinal vascular compromise contributing to the minimal expansion of the dye into serous cavity late into the study. No optic pit was discernible using optical coherence tomography imaging or fluorescein angiography.

CONCLUSIONS

Although glaucomatous damage of the optic nerve has rarely been shown to predispose an individual to serous complications within the macula, recent reports attest to its pathogenic capacity and propose a theory to explain their infrequent clinical coexistence. This case provides additional support for the mounting evidence to support the role of a compromised inner-limiting membrane in inducing a macular detachment in the setting of chronically elevated intraocular pressure without evidence of preexisting optic pits.

Stratus Optical Coherence Tomography for Evaluating Optic Disc Pits Associated with Maculopathy Before and After Vitrectomy: Two Case Reports

Optic disc pit (ODP) can be either congenital or acquired. Congenital ODP is typically unilateral, and the visual acuity and visual field are normal unless associated with macular serous detachment, which occurs in about 25-75% of cases. Acquired ODP is known as an important risk factor for progressive visual field loss in glaucoma. The fundus finding of congenital ODP includes oval depression involving the optic disc, with or without macular serous detachment. We used third-generation Stratus optical coherence tomography (Straus OCT) to investigate the possible pathogenesis of ODP associated with maculopathy and to monitor the anatomic changes before and after treatment.

Pathological optic-disc cupping

PURPOSE OF REVIEW

Pathological optic-disc cupping is most often caused by glaucoma, but may be seen in many less-common neuro-ophthalmic conditions. The goal of this article is to examine a host of entities causing optic-disc cupping, present key differentiating characteristics and pathophysiologies, and outline diagnostic approaches.

RECENT FINDINGS

Multiple entities not associated with elevated intraocular pressure or glaucomatous optic-nerve disease may result in pathologic optic-nerve excavation. Even with the photography and imaging of today, it is still difficult for the clinician to accurately diagnose other causes of optic-disc cupping. Up to 20% of patients may be misdiagnosed and treated for glaucoma due to misinterpretation of the optic-disc cupping. Newer forms of imaging including optical coherence tomography may assist the clinician in decision making. A scrutinizing history, close observation of disc appearance, and the vasculature will aid in the diagnosis of glaucoma or other entity of optic-disc cupping.

SUMMARY

Optic-disc cupping is a consequence of myriad disorders. Knowledge of the anatomy and vasculature of the disc is quintessential to the understanding of how, why, when, and what type of optic-disc cupping occurs in various conditions. Cupping can be seen with neurological processes, including benign tumors, which are treatable. Patient history, visual fields assessment, and funduscopic findings are the key to unlocking the diagnosis of glaucomatous versus nonglaucomatous optic-disc cupping. As clinicians, we must remain vigilant and receptive to the findings of potentially ominous forms of nonglaucomatous optic-disc cupping.

Three dimensional analysis of the lamina cribrosa in glaucoma

BACKGROUND/AIM

Structural changes in the lamina cribrosa have been implicated in the pathogenesis of glaucomatous optic atrophy. The aim of this study was to determine a measure the surface variability of the cup floor in normal subjects and patients with glaucoma.

METHODS

A sample of age matched normal subjects (NN), patients with low tension glaucoma (LTG), and primary open angle glaucoma (POAG) were included in the study. The glaucoma groups were matched for the severity of the visual field loss. Mean 10 degree topographic images of normal and glaucomatous eyes from the Heidelberg retina tomograph were imported into ERDAS image processing software where topographic analysis of the cup floor could be assessed. Each image was processed using customised spatial filters that calculated the surface depth variation in localised neighbourhood areas across each image. The local change in depth across the cup floor surface was determined and compared between the three clinical groups.

RESULTS

The depth variation in the cup floor was largest in normal subjects followed by LTG and POAG. Highly statistically significant differences in surface depth variability of the cup floor existed between normal and LTG (p = 0.005), between normal and POAG (p<0.0001), and between LTG and POAG groups (p<0.0001). The variability and skewness of depth difference across the optic cup floor were also significantly different between the three clinical groups.

CONCLUSION

A new parameter quantifying depth variations in the cup floor significantly discriminated between groups of normal and glaucoma patients. This new parameter may contribute to a better understanding of the pathogenesis of the glaucomatous optic nerve damage in different types of glaucoma.

Rate of Optic Disc Cup Progression in Treated Primary Open-Angle Glaucoma

PURPOSE

To quantitatively evaluate the rate of cup-to-disc ratio progression in treated patients with primary open-angle glaucoma and to identify clinical factors associated with cup progression.

PATIENTS AND METHODS

Fifty one eyes of 51 treated primary open-angle glaucoma patients with a minimum of 9-year longitudinal series of stereoscopic optic disc photographs were studied. Eyes with any other ocular disease except for mild cataract were excluded. Each set of stereoscopic photographs was digitized and viewed stereoscopically on a computer screen using a hand-held stereoscope. Computer-aided planimetry was performed on each set of photographs with examiner-defined cup and disc margins using custom-made software. The software computed linear cup-to-disc ratios as well as peripapillary atrophy area. Both inter-observer and intra-observer reliabilities were evaluated in a masked, random fashion using intra-class correlation. Changes in linear cup-to-disc ratios and peripapillary atrophy were estimated using linear regression over time. All available clinical factors were evaluated for association with the rate of cup progression using a multiple regression model.

RESULTS

All patients studied were Caucasian; 31(61%) were females. The mean age at the beginning of the study was 61.6 +/- 7.8 years (range 46-81). The mean follow-up period was 14.3 +/- 3.5 years (median 14.0, range 9.6-22.3). A total of 173 sets of stereo disc photographs were analyzed (3.4 +/- 1.3 per patient). The initial and final linear cup-to-disc ratios were 0.64 +/- 0.15 and 0.73 +/- 0.14 respectively. The inter-rater and intra-rater intraclass correlations were 0.76 (95% CI 0.61-0.87) and 0.97 (95% CI 0.93-0.98) respectively. Using linear regression the rate of linear cup-to-disc ratio change was 0.0068 +/- 0.0062 per year (range -0.0025- 0.0269). Three eyes had an increase in the peripapillary atrophy area. The higher yearly average intraocular pressure was significantly associated with faster rate of linear cup-to-disc ratios progression (P = 0.03).

CONCLUSIONS

In treated patients with primary open-angle glaucoma, the rate of progressive optic disc cupping was slow (LCDR progression of 0.0068 per year). The higher yearly average intraocular pressure was significantly associated with a faster rate of cup progression.