INCB24360 (Epacadostat), a Highly Potent and Selective Indoleamine-2,3-dioxygenase 1 (IDO1) Inhibitor for Immuno-oncology

A data-centric medicinal chemistry approach led to the invention of a potent and selective IDO1 inhibitor 4f, INCB24360 (epacadostat). The molecular structure of INCB24360 contains several previously unknown or underutilized functional groups in drug substances, including a hydroxyamidine, furazan, bromide, and sulfamide. These moieties taken together in a single structure afford a compound that falls outside of “drug-like” space. Nevertheless, the in vitro ADME data is consistent with the good cell permeability and oral bioavailability observed in all species (rat, dog, monkey) tested. The extensive intramolecular hydrogen bonding observed in the small molecule crystal structure of 4f is believed to significantly contribute to the observed permeability and PK. Epacadostat in combination with anti-PD1 mAb pembrolizumab is currently being studied in a phase 3 clinical trial in patients with unresectable or metastatic melanoma.

First-in-Human Phase I Study of the Oral Inhibitor of Indoleamine 2,3-Dioxygenase-1 Epacadostat (INCB024360) in Patients with Advanced Solid Malignancies

Purpose: Indoleamine 2,3-dioxygenase-1 (IDO1) catalyzes the degradation of tryptophan to N-formyl-kynurenine. Overexpressed in many solid malignancies, IDO1 can promote tumor escape from host immunosurveillance. This first-in-human phase I study investigated the maximum tolerated dose, safety, pharmacokinetics, pharmacodynamics, and antitumor activity of epacadostat (INCB024360), a potent and selective inhibitor of IDO1.Experimental Design: Fifty-two patients with advanced solid malignancies were treated with epacadostat [50 mg once daily or 50, 100, 300, 400, 500, 600, or 700 mg twice daily (BID)] in a dose-escalation 3 + 3 design and evaluated in 28-day cycles. Treatment was continued until disease progression or unacceptable toxicity.Results: One dose-limiting toxicity (DLT) occurred at the dose of 300 mg BID (grade 3, radiation pneumonitis); another DLT occurred at 400 mg BID (grade 3, fatigue). The most common adverse events in >20% of patients overall were fatigue, nausea, decreased appetite, vomiting, constipation, abdominal pain, diarrhea, dyspnea, back pain, and cough. Treatment produced significant dose-dependent reductions in plasma kynurenine levels and in the plasma kynurenine/tryptophan ratio at all doses and in all patients. Near maximal changes were observed at doses of ≥100 mg BID with >80% to 90% inhibition of IDO1 achieved throughout the dosing period. Although no objective responses were detected, stable disease lasting ≥16 weeks was observed in 7 of 52 patients.Conclusions: Epacadostat was generally well tolerated, effectively normalized kynurenine levels, and produced maximal inhibition of IDO1 activity at doses of ≥100 mg BID. Studies investigating epacadostat in combination with other immunomodulatory drugs are ongoing. Clin Cancer Res; 23(13); 3269-76. ©2017 AACR.

Population Pharmacokinetic and Pharmacodynamic Modeling of Epacadostat in Patients With Advanced Solid Malignancies

Epacadostat (EPA, INCB024360) is a selective inhibitor of the enzyme indoleamine 2,3-dioxygenase 1 (IDO1) and is being developed as an orally active immunotherapy to treat advanced malignancies. In the first clinical study investigating the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of EPA in oncology patients, increasing doses of EPA ranging from 50 mg once daily to 700 mg twice daily were administered as a monotherapy to 52 subjects with advanced solid tumors. The EPA plasma concentration-time profiles were adequately described by a population PK model comprised of the first-order kinetics of oral absorption with 2-compartment distribution and constant clearance from the central compartment. Body weight was the only significant covariant to influence EPA PK. Determination of EPA's on-target potency, ie, its half-maximal inhibitory concentration (IC₅₀ ) against IDO1, is important for dose selection but complicated by the bioconversion of tryptophan (TRP) to kynurenine (KYN) catalyzed by both IDO1 and TRP 2,3-dioxygenase (TDO). In vitro and ex vivo, the IC₅₀ was estimated following the selective induction of IDO1, rendering the TDO activity relatively insignificant; however, it was desirable to determine the in vivo IC₅₀ without inducing an IDO1 abundance. A mechanistic population PD model was developed based on time-matched EPA, TRP, and KYN plasma concentrations in 44 oncology patients, and EPA in vivo IC₅₀ was estimated to be ∼70 nM, consistent with the ex vivo value independently determined. The model suggests that ∼60% and 40% of TRP→KYN bioconversion was mediated by IDO1 and TDO, respectively, in the cancer patients at baseline. For this study population of limited numbers of subjects, neither age nor sex was a significant covariate for EPA PK or PD.

Hydroxyamidine inhibitors of indoleamine-2,3-dioxygenase potently suppress systemic tryptophan catabolism and the growth of IDO-expressing tumors

Malignant tumors arise, in part, because the immune system does not adequately recognize and destroy them. Expression of indoleamine-2,3-dioxygenase (IDO; IDO1), a rate-limiting enzyme in the catabolism of tryptophan into kynurenine, contributes to this immune evasion. Here we describe the effects of systemic IDO inhibition using orally active hydroxyamidine small molecule inhibitors. A single dose of INCB023843 or INCB024360 results in efficient and durable suppression of Ido1 activity in the plasma of treated mice and dogs, the former to levels seen in Ido1-deficient mice. Hydroxyamidines potently suppress tryptophan metabolism in vitro in CT26 colon carcinoma and PAN02 pancreatic carcinoma cells and in vivo in tumors and their draining lymph nodes. Repeated administration of these IDO1 inhibitors impedes tumor growth in a dose- and lymphocyte-dependent fashion and is well tolerated in efficacy and preclinical toxicology studies. Substantiating the fundamental role of tumor cell-derived IDO expression, hydroxyamidines control the growth of IDO-expressing tumors in Ido1-deficient mice. These activities can be attributed, at least partially, to the increased immunoreactivity of lymphocytes found in tumors and their draining lymph nodes and to the reduction in tumor-associated regulatory T cells. INCB024360, a potent IDO1 inhibitor with desirable pharmaceutical properties, is poised to start clinical trials in cancer patients.

Carbonic anhydrase IX expression and outcome after radiotherapy for muscle-invasive bladder cancer

AIMS

Carbonic anhydrase IX (CA IX) expression has been described as an endogenous marker of hypoxia in solid neoplasms. Furthermore, CA IX expression has been associated with an aggressive phenotype and resistance to radiotherapy. We assessed the prognostic significance of CA IX expression in patients with muscle-invasive bladder cancer treated with radiotherapy.

MATERIALS AND METHODS

A standard immunohistochemistry technique was used to show CA IX expression in 110 muscle-invasive bladder tumours treated with radiotherapy. Clinicopathological data were obtained from medical case notes.

RESULTS

CA IX immunostaining was detected in 89 ( approximately 81%) patients. Staining was predominantly membranous, with areas of concurrent cytoplasmic and nuclear staining and was abundant in luminal and perinecrotic areas. No significant correlation was shown between the overall CA IX status and the initial response to radiotherapy, 5-year bladder cancer-specific survival or the time to local recurrence.

CONCLUSIONS

The distribution of CA IX expression in paraffin-embedded tissue sections seen in this series is consistent with previous studies in bladder cancer, but does not provide significant prognostic information with respect to the response to radiotherapy at 3 months and disease-specific survival after radical radiotherapy.

Measurements using the alkaline comet assay predict bladder cancer cell radiosensitivity

In the UK, the two main treatments of invasive bladder cancer are radiotherapy or cystectomy. However, ∼50% of patients undergoing radiotherapy fail to respond. If tumour radiosensitivity could be predicted in advance, it may be possible to improve control rates significantly by selecting for radiotherapy those patients whose tumours are radiosensitive. Additionally, patients who would benefit from surgery would be identified earlier. The alkaline comet assay (ACA) is a sensitive method for the detection of DNA strand break damage in cells. In the present study, using six bladder cancer cell lines of differing radiosensitivities, cell survival was compared to the manifestation of radiogenic DNA damage as assessed by ACA. For all the cell lines, the extent of comet formation strongly correlates with cell killing (R²>0.96), with a greater response being noted in radiosensitive cells. In repair studies, measures of residual damage correlate with survival fraction at 2 Gy (R²>0.96), but for only five of the cell lines. Finally, cells from human bladder tumour biopsies reveal a wide range of predicted radiosensitivies as determined by ACA. Overall, these studies demonstrate ACA to be a good predictive measure of bladder cancer cell radiosensitivity at low dose, with potential clinical application.

Evaluation of phosphodiesterase I-based protocols for the detection of multiply damaged sites in DNA: the detection of abasic, oxidative and alkylative tandem damage in DNA oligonucleotides

It has been proposed that DNA multiply damaged sites (MDS), where more than one moiety in a local region ( approximately 1 helical turn, 10 bp) of the DNA is damaged, are lesions of enhanced biological significance. However, other than indirect measures, there are few analytical techniques that allow direct detection of MDS in DNA. In the present study we demonstrate the potential of protocols incorporating an exonucleolytic snake venom phosphodiesterase (SVPD) digestion stage to permit the direct detection of certain tandem damage, in which two lesions are immediately adjacent to each other on the same DNA strand. A series of prepared oligonucleotides containing either single or pairs of tetrahydrofuran moieties (F), thymine glycol lesions (T(g)) or methylphosphotriester adducts (Me-PTE) were digested with SVPD and the digests examined by either (32)P-end-labelling or electrospray mass spectrometry. The unambiguous observation of SVPD-resistant 'trimer' species in the digests of oligonucleotides containing adjacent F, T(g) and Me-PTE demonstrates that the SVPD digestion strategy is capable of allowing direct detection of certain tandem damage. Furthermore, in studies to determine the specificity of SVPD in dealing with pairs of lesions on the same strand, it was found mandatory to have the two lesions immediately adjacent to each other in order to generate the trimer species; pairs of lesions separated by as few as one or two normal nucleotides behave principally as single lesions towards SVPD.

Differential effects of the poly (ADP-ribose) polymerase (PARP) inhibitor NU1025 on topoisomerase I and II inhibitor cytotoxicity in L1210 cells in vitro

The potent novel poly(ADP-ribose) polymerase (PARP) inhibitor, NU1025, enhances the cytotoxicity of DNA-methylating agents and ionizing radiation by inhibiting DNA repair. We report here an investigation of the role of PARP in the cellular responses to inhibitors of topoisomerase I and II using NU1025. The cytotoxicity of the topoisomerase I inhibitor, camptothecin, was increased 2.6-fold in L1210 cells by co-incubation with NU1025. Camptothecin-induced DNA strand breaks were also increased 2.5-fold by NU1025 and exposure to camptothecin-activated PARP. In contrast, NU1025 did not increase the DNA strand breakage or cytotoxicity caused by the topoisomerase II inhibitor etoposide. Exposure to etoposide did not activate PARP even at concentrations that caused significant levels of apoptosis. Taken together, these data suggest that potentiation of camptothecin cytotoxicity by NU1025 is a direct result of increased DNA strand breakage, and that activation of PARP by camptothecin-induced DNA damage contributes to its repair and consequently cell survival. However, in L1210 cells at least, it would appear that PARP is not involved in the cellular response to etoposide-mediated DNA damage. On the basis of these data, PARP inhibitors may be potentially useful in combination with topoisomerase I inhibitor anticancer chemotherapy.

A statistical-based approach to assessing the fidelity of combinatorial libraries encoded with electrophoric molecular tags. Development and application of tag decode-assisted single bead LC/MS analysis

A statistical sampling protocol is described to assess the fidelity of libraries encoded with molecular tags. The methodology, termed library QA, is based on the combined application of tag decode analysis and single bead LC/MS. The physical existence of library compounds eluted from beads is established by comparing the molecular weight predicted by tag decode with empirical measurement. The goal of sampling is to provide information on overall library fidelity and an indication of the performance of individual library synthons. The minimal sampling size n for library QA is l0 x the largest synthon set. Data are reported as proportion (p) +/- lower and upper boundary (lb-ub) computed at the 95% confidence level (alpha = 0.05). As a practical demonstration, library QA was performed on a 25,200-member library of statine amides (size = 40 x 63 x 10). Sampling was conducted three times at n approximately 630 beads per run for a total of 1902 beads. The overall proportions found for the three runs were consistent with one another: p = 84.4%, lb-ub = 81.5-87.2%; p = 83.1%, lb-ub = 80.2-85.95; and p = 84.5%, lb-ub = 81.8-87.3%, suggesting the true value of p is close to 84% compound confirmation. The performance pi of individual synthons was also computed. Corroboration of QA data with biological screening results obtained from assaying the library against cathepsin D and plasmepsin II is discussed.

Resistance-modifying agents. Part 7: 2,6-disubstituted-4,8-dibenzylaminopyrimido[5,4-d]pyrimidines that inhibit nucleoside transport in the presence of alpha1-acid glycoprotein (AGP)

The synthesis and biological evaluation of potent 4,8-dibenzylaminopyrimidopyrimidine nucleoside transport inhibitors, with reduced binding to alpha1-acid glycoprotein, is reported.

Potentiation of the cytotoxicity of thymidylate synthase (TS) inhibitors by dipyridamole analogues with reduced alpha1-acid glycoprotein binding

Dipyridamole has been shown to enhance the in vitro activity of antimetabolite anticancer drugs through the inhibition of nucleoside transport. However, the clinical potential of dipyridamole has not been realized because of the avid binding of the drug to the plasma protein alpha1-acid glycoprotein (AGP). Dipyridamole analogues that retain potent nucleoside transport inhibitory activity in the presence of AGP are described and their ability to enhance the growth inhibitory and cytotoxic effects of thymidylate synthase (TS) inhibitors has been evaluated. Three dipyridamole analogues (NU3026, NU3059 and NU3060) were shown to enhance the growth inhibitory activity of the TS inhibitor CB3717 and block thymidine rescue in L1210 cells. The extent of potentiation at a fixed analogue concentration (10 microM) was related to the potency of inhibition of thymidine uptake. A further analogue, NU3076, was identified, which was more potent than dipyridamole with a Ki value for inhibition of thymidine uptake of 0.1 microM compared to 0.28 microM for dipyridamole. In marked contrast to dipyridamole, inhibition of thymidine uptake by NU3076 was not significantly affected by the presence of AGP (5 mg ml(-1)). NU3076 and dipyridamole produced equivalent potentiation of the cytotoxicity of the non-classical antifolate TS inhibitor, nolatrexed, in L1210 cells with both compounds significantly reducing the LC90, by > threefold in the absence of salvageable thymidine. Thymidine rescue of L1210 cells from nolatrexed cytotoxicity was partially blocked by both 1 microM NU3076 and 1 microM dipyridamole. NU3076 also caused a significant potentiation of FU cytotoxicity in L1210 cells. These studies demonstrate that nucleoside transport inhibition can be maintained in the absence of AGP binding with the dipyridamole pharmacophore and that such analogues can enhance the cytotoxicity of TS inhibitors.

Potentiation of anti-cancer agent cytotoxicity by the potent poly(ADP-ribose) polymerase inhibitors NU1025 and NU1064

The ability of the potent poly(ADP-ribose) polymerase (PARP) inhibitor, NU1025 (8-hydroxy-2-methyl-quinazolin-4-[3H]one) to potentiate the cytotoxicity of a panel of mechanistically diverse anti-cancer agents was evaluated in L1210 cells. NU1025 enhanced the cytotoxicity of the DNA-methylating agent MTIC, gamma-irradiation and bleomycin 3.5-, 1.4- and 2-fold respectively. The cytotoxicities of the thymidylate synthase inhibitor, nolatrexed, and the cytotoxic nucleoside, gemcitabine, were not increased. Potentiation of MTIC cytotoxicity by a delayed exposure to NU1025 was equally effective as by a simultaneous exposure to NU1025, indicating that the effects of NU1025 were mediated by an inhibition of the cellular recovery. The recovery from potentially lethal gamma-irradiation damage cytotoxicity in plateau-phase cells was also inhibited by NU1025. Investigation of DNA strand breakage and repair in gamma-irradiated cells by alkaline elution demonstrated that NU1025 caused a marked retardation of DNA repair. A structurally different PARP inhibitor, NU1064 (2-methylbenzimidazole-4-carboxamide), also potentiated the cytotoxicity of MTIC, to a similar extent to NU1025. NU1064 potentiated a sublethal concentration of a DNA methylating agent in a concentration-dependent manner. Collectively, these data suggest that the most suitable cytotoxic agents for use in combination with PARP inhibitors are methylating agents, bleomycin and ionizing radiation, but not anti-metabolites.

The use of colour difference vectors in diagnosing congenital colour vision deficiencies with the Farnsworth-Munsell 100-hue test

Colour difference vector analysis provides useful and meaningful information in scoring the Farnsworth-Munsell (FM) 100-hue test. However, the FM 100-hue test is limited in its ability to diagnose type and severity of congenital colour vision defect. Type classification for all subjects is incorrect in 21% of cases, and for deuteranomals the misclassification rate is 38%. Visual inspection of the plots yields a similar misclassification rate and classification of plots with few errors (under 180) is generally less reliable. The FM 100-hue test has a limited ability to separate dichromats from anomalous trichromats. A test protocol based on joint D15 and FM 100-hue tests should pass 36% of anomalous trichromats and 26% of all colour defectives yet fail all dichromatic observers. We conclude that administering the FM 100-hue test is of less value than a combination of D15 panels (Standard D15 and L'Anthony's desaturated D15) in the clinical diagnosis of congenital colour defective observers. Our results for the FM 100-hue panel are similar to those reported previously by other investigators.

Task variables and visual discomfort associated with the use of VDT's

We investigated task variables that may influence the incidence of visual discomfort amongst subjects who routinely spent a proportion of their day working with visual display terminals (VDT's). A diary was kept by subjects over five consecutive working days, in which they recorded visual symptoms, the visual tasks undertaken, the amount of time spent on workbreaks, work pressure, work interest, and personal moderating factors which may have influenced the symptoms recorded. The symptoms recorded by subjects were then treated as dependent variables in multiple regression analyses with the diary findings (task-related factors) as independent variables. The incidence of some types of symptoms was significantly associated with specific categories of work tasks, personal moderating influences, work pressure, work interest, time of day, and day of week.

Quantitative scoring methods for D15 panel tests in the diagnosis of congenital color vision deficiencies

Farnsworth's standard D15 and L'Anthony's desaturated D15 panel tests were administered to 99 congenital red-green color defective subjects. The results were analyzed in three ways: (1) by summing the color differences between adjacent caps according to Bowman, (2) by averaging color difference vectors (CDV) according to Vingrys and King-Smith, and (3) by visually inspecting and counting the crossings. The Bowman measure was highly correlated with one of the CDV measures but provides less information regarding a cap arrangement. The desaturated D15 test can be expected to misclassify 5% of dichromats by type (protan/deutan) compared to a type misclassification rate of less than 0.1% for the D15 panel test. The correct diagnostic rates for type were 45% for the standard D15 test and 58% for the desaturated D15 test. However, the improvement in correct diagnostic rate for the latter test was accompanied by an increase in the misdiagnostic rate from 2 to 10%. The main value of the desaturated D15 test in congenital color vision diagnosis would seem to be in providing classification of those subjects who pass the standard D15 test. Quantitative scoring of the tests provides a good estimate of severity of defect. Visual inspection provides a similar diagnostic rate to CDV analysis, but has a lower type misdiagnostic rate at the desaturated D15 test and is more likely to be correct when the two methods disagree. We suggest that quantitative scoring techniques are of limited benefit for the clinical diagnosis of congenital color vision defects but that they are of use in clinical trials or for the monitoring of changes in color vision over time.(ABSTRACT TRUNCATED AT 250 WORDS)

Peripheral visual acuity and age

We measured the peripheral visual acuity of a group of eleven older subjects (mean age 54.2 years) and a group of seventeen young subjects (mean age 22.1 years). Peripheral visual acuity was measured using Konig bars with critical detail subtending 2.4 and 4.8 minutes of arc. The older group showed a substantial reduction of peripheral visual acuity.

Detection of change of size by young and old observers

Thresholds for detecting change of angular size were determined for a range of angular separations in young and elderly observers. We found no differences in thresholds between these subjects groups. Thresholds for detection of change of visual angle increased with angular separation in a power function relationship. Angular size change judgements based on successive views of a target are apparently not significantly affected by age.

Spatial summation in young and elderly observers

We measured detection thresholds for targets over a range of sizes at both photopic and scotopic luminance levels in young and elderly observers, and used these data to estimate spatial summation areas 10 degrees in the retinal periphery. There were differences in detection thresholds between the young and old groups at photopic and scotopic luminances, but no differences in spatial summation areas at either background luminance level.

Peripheral visual acuity with monovision and other contact lens corrections for presbyopia

We have conducted two experiments to investigate the effect of monovision and other contact lens corrections for presbyopia upon peripheral visual acuity. In the first study, we measured binocular peripheral visual acuity using Landolt rings with seven subjects wearing a monovision correction. The Landolt rings were presented at eccentricities of 10, 20, 40, and 70 degrees on each side of the subject, with near additions of +1.50 D, +2.50 D, and no addition. We found no significant effect of monovision correction on peripheral visual acuity. In the second experiment we measured the peripheral visual acuity of 11 presbyopic subjects wearing distance contact lenses with lookover spectacles, soft progressive bifocal contact lenses, soft concentric bifocal contact lenses, monovision contact lenses, modified monovision contact lenses, and hard bifocal contact lenses using Koenig bar targets. There were no significant differences in peripheral visual acuity between any of the contact lens corrections for presbyopia.

Contrast sensitivity with contact lens corrections for presbyopia

We measured contrast sensitivity at three distances (330 mm, 660 mm and 4 m) with six contact lens and two multifocal spectacle corrections for presbyopia. The two spectacle corrections were D-segment bifocals and trifocals and the contact lens corrections were distance contact lens with lookover spectacles, soft progressive bifocals, soft concentric bifocals, monovision, modified monovision, and hard crescent segment bifocals. The spectacle corrections in general gave better results for the contrast sensitivity function (CSF), than did the contact lens corrections. Distance contact lenses with lookover spectacles performed best of the contact lens corrections used. However, the differences in CSF between the various contact lens corrections were small and not statistically significant.

Sensitivity to changes in size and velocity in young and elderly observers

Thresholds for detection of change of size and for detection of change of velocity were measured in young and elderly observers. No differences in thresholds between these subject groups were found at the fovea or in more peripheral retina. The results indicate a degree of functional redundancy in the peripheral retina of elderly subjects, even though there is evidence of reduced numbers of functional photoreceptors in the periphery.

A method for quantitative scoring of the Farnsworth Panel D-15

The Farnsworth Dichotomous test or Panel D-15 is used extensively for the evaluation of colour discrimination in congenital and acquired colour vision defects. This qualitative assessment of colour vision defect type and severity is based on the hue confusions which are represented diagrammatically on the Panel D-15 score sheet. This paper presents a new proposal for quantitatively scoring the Panel D-15 based on those hue confusions made by the subject. Such a quantitative score can be used to establish relationships with other visual functions or experimental conditions. The application of the scoring technique to clinical results is illustrated.

Recognition of the aircraft navigation light color code

Navigation lights are a set of color-coded signals intended to indicate the presence, orientation, and relative direction of aircraft at night, and thereby reduce the possibility of midair collisions. It is known that some people with defective color vision have difficulty with quite simple codes. Accordingly, the International Civil Aviation Organization (ICAO) has recommended -- and most countries apply -- that applicants for pilot's licences demonstrate the ability to recognise colored light signals. Pilots who fail to meet this requirement are restricted from flying at night. But is the navigation light signal system effective? This paper concludes that the navigation light system at night can serve as a crude screening method to categorize intruder aircraft into "potential threat" and "no threat" categories. An experiment is described which shows that observers with normal color vision can determine intruder aircraft orientation and relative direction from the navigation light code with a moderately high degree of reliability. The reliability of judgement is, however, decreased by the higher-intensity presence lights also displayed by aircraft.

The role of corneal distortion in the occurrence of monocular diplopia

The measurement of anterior corneal surface topography before and during the occurrence of monocular diplopia can be used to predict the angular positions of any secondary images resulting from corneal distortion. The predictions correlate at a statistically significant level with direct measurements of the positions of the secondary images.

A recommendation for illumination of the Farnsworth-Munsell 100-hue test

The effect of illuminance on the performance of the Farnsworth-Munsell 100-hue (FM 100) test has previously been reported for young observers with normal color vision. However, information regarding these effects for older persons is lacking. This study reports the effect of illuminance level, over a wide range, on the FM100 performance of 10 elderly subjects with normal color vision compared to a control group of five young adult normal subjects. A recommendation is made for a standard level of illuminance for administration of the FM100-hue test.

The clinical assessment of colour discrimination in senile macular degeneration

The colour discrimination of 15 subjects manifesting senile macular degeneration was investigated, over a wide range of illuminances, using the Farnsworth-Munsell 100-Hue test and Panel D-15. Ten subjects of similar ages with normal colour vision were investigated concurrently to provide a control group. Colour discrimination was shown to deteriorate with decreasing illuminance this being more marked for the subjects with senile macular degeneration than for the normal subjects. It is demonstrated that the FM 100 is the preferred test for assessment of colour discrimination loss in senile macular degeneration with early visual acuity loss. The Panel D-15 is more useful as acuity loss becomes more marked.

The relationship between color discrimination and visual acuity in senile macular degeneration

The course of ocular disease can be monitored by the assessment and measurement of a number of visual functions. In the clinical situation, visual acuity and color discrimination are obvious and simple functions to assess. The relationship between color vision and visual acuity in eye disease has generally been discussed only in qualitative terms. This paper examines the correlation between visual acuity and color discrimination for a number of subjects exhibiting varying degrees of severity of senile macular degeneration.

Bilateral keratoconus posticus circumscriptus: a case report

The characteristics, clinical appearance, and frequency of the rare corneal condition, keratoconus posticus circumscriptus, are discussed. A bilateral case of this condition, examined by use of techniques not previously employed, is described.

The effect of non-contact tonometry on corneal topography

A sensitive photokeratoscope was used to determine the effect on corneal topography of non-contact tonometry in six subjects. No corneal distortion was detected.

Corneal topography and monocular diplopia following near work

Monocular diplopia, reported by a subject following near work, was shown to be caused by changes in the corneal topography. Prior slit lamp biomicroscopy had revealed no corneal abnormality. The degree of corneal distortion and ray tracing calculations confirmed the presence and position of the resultant diplopia.