Influence of glaucoma surgery on the ocular surface using oculus keratograph.

PURPOSE: To investigate the influence of trabeculectomy and phacotrabeculectomy on the ocular surface. DESIGN: Retrospective, case-control study. METHODS: Eighty-one samples without dry eyes were recruited and divided into three groups, including phacoemulsification group (N = 30) as control group, trabeculectomy group (N = 27) and phacotrabeculectomy group (N = 24) as study groups. Ocular surface parameters, including noninvasive keratograph first (NifBUT) and average (NiaBUT) tear film breakup time, tear meniscus height (TMH) and corneal fluorescein stain (CFS), were estimated preoperatively, at 3 days, 1 month and 3 months postoperatively using oculus keratograph. RESULTS: No significant difference was observed in ocular surface parameters at baseline among three groups (p > 0.05). The magnitude of NifBUT and NiaBUT was reduced at 3 days and 1 month postoperatively in phacotrabeculectomy group, but greater than that in the other two groups (All p < 0.001). In all the groups, both the NifBUT and NiaBUT tended to recover at 1 and 3 months postoperatively, whereas both of them did not recover to baseline at 3 months postoperatively in trabeculectomy (NifBUT, p = 0.001; NiaBUT, p < 0.001) and phacotrabeculectomy group (NifBUT, p < 0.001; NiaBUT, p = 0.020). TMH was raised at 3 days postoperatively and restored to the baseline level at 1 and 3 months postoperatively for three groups (p > 0.05). CFS was elevated at 3 days postoperatively and different in recovery at 1 and 3 months postoperatively for three groups. CONCLUSIONS: The influence of phacotrabeculectomy on ocular surface is worse than that of trabeculectomy for the short run and is not distinct different for a long time.

Surround Propinquity and Tonic Accommodation.

PURPOSE: Previous studies of dark focus have found evidence of a propinquity response, in which subjects accommodate to the perceived distance of their surroundings despite being in absolute darkness. Their distance perception in a lighted room allows a spatial representation to persist within the darkened room. This study sought to establish the significance and magnitude of the propinquity response in a large sample of young adults, and to determine whether the propinquity response can be predicted by a subject's initial dark focus in an unknown dark room. METHODS: Dark focus was measured with a dynamic infrared optometer (Plusoptix PowerRef 3) in 30 young adult subjects, 26 of whom were naive to the testing room and its dimensions. Dark focus was then measured at varying dioptric wall distances of 0.25-4D. The subject viewed the lighted room before each measurement. For each individual, the dark focus was plotted as a function of dioptric wall distance. The slope of this function was used as a measure of the propinquity response. RESULTS: The mean initial dark focus value was 1.05D (SD 1.04D) for the 26 naive subjects. The mean slope of the plot of dark focus as a function of dioptric wall distance was small (+0.097), yet highly statistically significant (P = .0002). The propinquity response function showed no statistically significant quadratic or cubic trends, and so may be considered linear. No statistically significant correlation was found between naive dark focus and propinquity response (r = +0.246, P = .226). CONCLUSIONS: Propinquity seems to be a small but statistically significant factor in dark focus measurements. Though it is unlikely to contaminate tonic accommodation measurements in large samples under normal laboratory conditions, a minority of individuals exhibit large propinquity responses equal to that of proximal accommodation in lighted conditions.

Accommodation stimulus and response determinations with autorefractors.

PURPOSE: To develop equations for accommodation stimulus and accommodation response with autorefractors when the accommodation stimulus is produced by combinations of object distances and lenses placed in front of eyes, and to give worked examples using these equations. METHODS: Simple ray tracing was used to determine stimulus and response equations, taking into account the reference positions for targets, for refraction, and for autorefractor readings. RESULTS: Several examples applying equations are provided. Features of these examples include evaluating approximate calculations that have been used previously, demonstrating which equations should be used in different circumstances, how to substitute numbers into equations, how to deal with discrepancies between subjective and objective refraction, and how to deal with astigmatism. Problems associated with measuring accommodation response by placing lenses in front of the eye are discussed. CONCLUSIONS: Accurate equations for accommodation stimulus and accommodation response for a range of accommodation stimuli in different setups have been developed.

Does the Badal optometer stimulate accommodation accurately?

PURPOSE: To study whether the accommodation response to Badal optometer is equivalent to the response for real space targets. METHODS: Accommodative responses were measured for 28 young eyes with the WAM-5500 autorefractometer in eight configurations for 0.17 D, 2.0 D and 5.0 D accommodation stimuli. Parameters that might contribute to differences in response were systematically isolated: stimulation method (real space vs Badal targets), field of view, instrument's cover proximity, the looming effect, and the peripheral interposition of objects in depth. RESULTS: Mean accommodative response differences between a natural view configuration and a configuration with a Badal Optometer were 0.50 ± 0.43 D and 0.58 ± 0.53 D for 2.0 D and 5.0 D stimulation, respectively (p < 0.001), with accommodation lags for the latter condition. Of the isolated parameters that might contribute to these differences, varying the interposition of objects in depth affected accommodation response more markedly. CONCLUSIONS: It is likely that Badal optometers affect accommodation through a combination of some or all of the studied parameters. We conclude that accommodation response to closed-view Badal optometers is not equivalent to real space target response.

[Accuracy of three common optometry methods in examination of refraction in juveniles].

OBJECTIVE: To compare the results of the three methods of Suresight handheld autorefractor, table-mounted autorefractor and retinoscopy in examination of juveniles patients with or without cycloplegia.
 METHODS: Firstly, 156 eyes of 78 juveniles (5 to 17 years old) were examined by using WelchAllyn Suresight handheld autorefractor and NIDEK ARK-510A table-mounted autorefractor with or without cycloplegia; secondly, retinoscopy was performed with cycloplegia.
 RESULTS: The spherical power measured by methods without cycloplegia were significantly greater than those measured with cycloplegia (P<0.05); without cycloplegia, there was no significant difference in spherical power, cylindrical power and cylindrical axis between Suresight handheld autorefractor and retinoscopy (P>0.05). These results were highly consistent, suggesting a tendency towards a short sight. However, the spherical power and cylindrical power measured by table-mounted autorefractor was significantly different (P<0.05); with cycloplegia, there was significant difference in spherical power between Suresight handheld autorefractor and retinoscopy (P<0.05).
 CONCLUSION: Cycloplegic retinoscopy is necessary for juvenile refraction examination. Under natural pupil situation, Suresight handheld autorefractor is better than table-mounted autorefractor, though both show a myopia tendency. Nevertheless, table-mounted autorefractor can be taken as a recommendation for the prescription of lens trial. As a strong reference for subjective optometry, retinoscopy should be the gold standard for measuring refractive errors.

PRESBYOPIA OPTOMETRY METHOD BASED ON DIOPTER REGULATION AND CHARGE COUPLE DEVICE IMAGING TECHNOLOGY.

With the development of photoelectric technology and single-chip microcomputer technology, objective optometry, also known as automatic optometry, is becoming precise. This paper proposed a presbyopia optometry method based on diopter regulation and Charge Couple Device (CCD) imaging technology and, in the meantime, designed a light path that could measure the system. This method projects a test figure to the eye ground and then the reflected image from the eye ground is detected by CCD. The image is then automatically identified by computer and the far point and near point diopters are determined to calculate lens parameter. This is a fully automatic objective optometry method which eliminates subjective factors of the tested subject. Furthermore, it can acquire the lens parameter of presbyopia accurately and quickly and can be used to measure the lens parameter of hyperopia, myopia and astigmatism.

Ocular surface sensitivity repeatability with Cochet-Bonnet esthesiometer.

PURPOSE: To determine the repeatability of ocular surface threshold measurements using the Cochet-Bonnet esthesiometer on the same day and 3 months apart. METHODS: Two separate studies were conducted to determine the repeatability of ocular surface threshold measurements made on the same day (n = 20 subjects) and 3 months apart (n = 29 subjects). The Cochet-Bonnet esthesiometer was used to measure corneal and inferior conjunctival thresholds using the ascending method of limits. The pressure exerted by the Cochet-Bonnet esthesiometer was determined using an analytical balance, for both the 0.08- and 0.12-mm-diameter filaments. This calibration was then used to convert filament length measurements to pressure. Repeatability was determined using a Bland and Altman analysis. RESULTS: The pressure exerted at each filament length differed between the two filament diameters. The measured pressure also differed from values provided by the manufacturer. Repeatability of threshold measurements at the central cornea was shown to be good, with better repeatability for same-day measurements (coefficient of repeatability [CoR] = ±0.23 g/mm²) than for those 3 months apart (CoR = ±0.52 g/mm²). Threshold measurements at the inferior conjunctiva, in contrast, were poorly repeatable (CoR = ±12.78 g/mm²). CONCLUSIONS: Cochet-Bonnet esthesiometry is repeatable when performed on the central cornea on the same day and 3 months apart, but this instrument is not recommended for conjunctival threshold measurements.

Clinical evaluation of the Shin-Nippon SRW-5000 autorefractor in adults: an update.

PURPOSE: The Shin-Nippon SRW-5000 is an open view autorefractor that superseded the Canon R-1 autorefractor in the mid-1990 s and has been used widely in optometry and vision science laboratories. It has been used to measure refractive error, accommodation responses both statically and dynamically, off-axis refractive error, and adapted to measure pupil size. This paper presents an overview of the original 2001 clinical evaluation of the SRW-5000 in adults (Mallen et al., Ophthal Physiol Opt 2001; 21: 101) and provides an update on the use and modification of the instrument since the original publication. RECENT FINDINGS: The SRW-5000 instrument, and the family of devices which followed, have shown excellent validity, repeatability, and utility in clinical and research settings. The instruments have also shown great potential for increased research functionality following a number of modifications. SUMMARY: The SRW-5000 and its derivatives have been, and continue to be, of significant importance in our drive to understand myopia progression, myopia control techniques, and oculomotor function in human vision.

Individually designed PALs vs. power optimized PALs adaptation comparison.

The practice shows that in everyday life we encounter ever-growing demand for better visual acuity at all viewing distances. The presbyopic population needs correction to far, near and intermediate distance with different dioptric powers. PAL lenses seem to be a comfortable solution. The object of the present study is the analysis of the factors determining adaptation to progressive addition lenses (PAL) of the first-time users. Only novice test persons were chosen in order to avoid the bias of previously worn particular lens design. For optimal results with this type of lens, several individual parameters must be considered: correct refraction, precise ocular and facial measures, and proper mounting of lenses into the frame. Nevertheless, first time wearers encounter various difficulties in the process of adapting to this type of glasses and adaptation time differs greatly between individual users. The question that arises is how much the individual parameters really affect the ease of adaptation and comfort when wearing progressive glasses. To clarify this, in the present study, the individual PAL lenses--Rodenstock's Impression FreeSign (with inclusion of all parameters related to the user's eye and spectacle frame: prescription, pupillary distance, fitting height, back vertex distance, pantoscopic angle and curvature of the frame) were compared to power optimized PAL--Rodenstock's Multigressiv MyView (respecting only prescription power and pupillary distance). Adaptation process was monitored over a period of four weeks. The collected results represent scores of user's subjective impressions, where the users themselves rated their adaptation to new progressive glasses and the degree of subjective visual impression. The results show that adaptation time to fully individually fit PAL is easier and quickly. The information obtained from users is valuable in everyday optometry practice because along with the manufacturer's specifications, the user's experience can give us a better insight in design and characteristics of progressive lenses.

The effect of pupillary dilatation on IOL power measurement by using the IOLMaster.

The aim of this study is to assess the agreement of IOL power and ocular biometry measurements before and after pupillary dilatation by using the IOLMaster. This was the prospective nonrandomized cohort study. Measurements were taken with the IOLMaster (®) (Carl Zeiss Meditec AG, Jena, Germany) from healthy volunteers at the Department of Ophthalmology, King Chulalongkorn Memorial Hospital. Axial length (AL), keratometry both flattest and steepest (K1, K2), and anterior chamber depth (ACD) were measured before and after the dilatation of the pupil with 1 % tropicamide. The IOL power was calculated using the Sanders-Retzlaff-Kraff/Theoretical (SRK/T) formula. The mean difference of each parameter was assessed by Bland-Altman plot analysis. 384 eyes from 195 healthy volunteers were measured. The mean age of the patients was 52.39 ± 1.02 years (range 21-79). Pupillary dilatation had no significant effect on AL (p = 0.07), keratometry [steepest K (p = 0.95) and flattest K (p = 0.17)], and IOL power (Alcon SN60WF) (p = 0.40) obtained from the IOLMaster. However, ACD was significantly increased post-dilatation (p < 0.05). The Bland-Altman plot indicated good concordance in nearly all parameters except ACD. For ACD measurements, the 95 % limit of agreement between pre-dilatation and post-dilatation was -0.47 to 0.23 mm; therefore, 92.2 % of the measurement differences were with a LoA of -0.47 to 0.23 mm. There were no eyes that could not be measured by the IOLMaster. The dilatation of the pupil had no significant effect on AL, keratometry measurements, and SRK/T calculated IOL power. However, the ACD significantly increased post-dilatation.

[Observation of orthokeratology discontinuation].

OBJECTIVE: To observe the change of teenagers with short-time and long-time orthokeratology discontinuation, including diopters, corneal curvature, corneal topography, axial length, and central corneal thickness, and to investigate the refractive correction methods after long-time orthokeratology discontinuation. METHODS: Retrospective study. A total of 141 patients (257 eyes) with a history of wearing and discontinuing wearing orthokeratology lenses in our center were collected. According to the spherical equivalent diopters, the patients were divided into two groups (< or = -4.00 D for group I and -4.00 D for group II). Each group was further divided into two sub-groups by the discontinuation time (1 to 3 months for sub-group A and more than 3 months for sub-group B). Four sub-groups were named as I A, II A, I B, and II B. Some optical examinations were performed for the patients before orthokeratology lens wearing and after orthokeratology discontinuation, such as refraction, corneal curvature, corneal topography, corneal endothelial cells, axial length, and central corneal thickness measurement. The refractive correction methods used by patients who had long-term orthokeratology discontinuation were recorded. The observed data were analyzed with paired t-test and one-way ANOVA by SPSS16. RESULTS: The statistically significant changes (t = 3.222, 3.404, 3.141, 5.012, P < 0.05) of spherical diopter values were (-0.31 +/- 0.58) D, (-0.48 +/- 0.68) D, (-0.35 +/- 0.65) D, and (-0.57 +/- 0.58) D for groups IA, IB, IIA, and IIB, respectively. astigmatism of the four sub-groups had no significant change (P > 0.05) The average annual spherical growth was (-0.08 +/- 0.17) D, (-0.12 +/- 0.17) D, (-0.07 +/- 0.19) D, and (-0.15 +/- 0.16) D, respectively, for the four sub-groups, and there was no statistically significant difference among them (F = 1.180, P > 0.05). Compared to the state before wearing orthokeratology lenses, the corneal curvature measured by an autorefractor was statistically different for groups I A and I A, but not statistically different for groups I B and II B. For the long-time discontinuation groups, only the SRI of the corneal topography had a statistically significant decrease compared to the value before wearing orthokeratology lenses, and others had no significant change. The average annual increase of axial length was (0.22 +/- 0.16) mm and (0.16 +/- 0.10) mm for groups IA and IB, respectively, and the increase was statistically significant (P < 0.05), but there was no significant difference between the two sub-groups (F = 1.908, P > 0.05). The central corneal thickness had no significant change (t = 1.971, 2.017, P > 0.05). The rates of the refractive correction methods after long-time discontinuation were 36.7%, 22.4%, 22.4%, 12.4%, and 6.1% for spectacles, rigid gas permeable contact lenses, soft contact lenses, either spectacles or soft contact lenses, and refractive operations, respectively. CONCLUSION: The corneal morphology and central corneal thickness returned to the original after three months of discontinuation of orthokeratology. The myopia had no significant growth after discontinuation, and there was no significant difference between low to moderate and relatively high myopia.

[Accommodation to monochromatic targets in people with different color vision statuses].

OBJECTIVE: To compare the accommodation response (AR) to monochromatic targets in subjects with different color vision statuses, and to investigate the role of color vision in the control of accommodation and emmetropization. METHODS: It was a case-control study. Accommodation was measured with a dynamic infrared optometer while subjects [17 protans, 47 deutans, and 23 normals; mean age: (20.0 ± 4.4) years] viewed a (1) red on black or (2) green on black vertical square-wave gratings of iso-luminance (3 cycles/deg; 0.9 contrast) in a Badal optic system. The grating stepped 1.00 D towards the eye from an initial position of 0 D until 5.00 D. RESULTS: With red-black targets, the AR in the protans (AR = 1.98 D) was worse than that in the normals (AR = 2.55 D) when the accommodation stimulus (AS) was 4.00 D (LSD, P = 0.031). The AR in the deutans were worse than that in the normals when the AS was 3.00, 4.00, and 5.00 D (3.00 D: 1.23 D vs. 1.69 D, P = 0.002; 4.00 D: 1.89 D vs. 2.55 D, P = 0.002; 5.00 D: 2.40 D vs. 3.17 D, P = 0.003). With green-black targets, the AR in the protans were worse than that in the normals when the AS was 3.00 and 4.00 D (3.00 D: 1.13 D vs. 1.61 D, P = 0.004; 4.00 D: 1.80 D vs. 2.34 D, P = 0.021). In the deutans, the AR was worse with stimuli of 3.00, 4.00, and 5.00 D (3.00 D: 1.21 D vs. 1.61 D, P = 0.003; 4.00 D: 1.65 D vs. 2.34 D, P < 0.001; 5.00 D: 2.36 D vs. 2.93 D, P = 0.007). No significant differences between the protans and deutans were found for all the stimulus conditions. In the protans, accommodation to red-black targets was better than that to green-black targets when the stimulus was 2.00, 3.00, and 5.00 D (2.00 D: t = -2.81, P = 0.013; 3.00 D: t = -4.55, P < 0.001; 5.00 D: t = -3.15, P = 0.006). In the deutans, accommodation to red-black targets was better than that to green-black targets when the stimulus was 4.00 D (t = -2.19, P = 0.034). In the normals, accommodation to red-black targets were better than that to green-black targets when the stimulus was 2.00, 4.00, and 5.00 D (2.00 D: t = -2.57, P = 0.017; 4.00 D, t = -2.67, P = 0.014; 5.00 D: t = -2.15, P = 0.043). CONCLUSIONS: Individuals with a color vision deficiency tend to have a larger accommodative lag than normals. Red targets tend to induce better accommodation response than green ones. Color vision may play a role in the control of accommodation and emmetropization.

A comparison of four different lens mappers.

PURPOSE: Recently, a number of lens mappers have become available for measuring the detailed optical properties of progressive addition lenses (PALs). The goal of this study was to compare the results obtained from several different lens mappers for a range of different lenses. METHODS: The optical power maps of six lenses-two single-vision lenses, a parallel-sided slide, a flat prism, and two progressive lenses-were measured using four different lens mappers: the Dual Lens Mapper, the Nimo TR4005, the Rotlex Class Plus, and the Visionix VM2500. The repeatability of the instruments was also evaluated. RESULTS: All lens mappers gave very repeatable measurements; however, measurements among the lens mappers varied considerably. Differences appeared to be above the tolerance at the optical center for measurements of single-vision lenses, and these differences increase in the periphery up to 1.00 diopter. Similar differences were observed for the PALs, even increased by prism and base curve effect, with figures greater than 1 diopter in the periphery. The measurements made on the prism and lenses with different base curves suggest that base curve, thickness, and prismatic effect can all contribute to the differences among instruments. CONCLUSIONS: Measurements of a given lens taken with different lens mappers can vary substantially. Particular caution should be exercised when interpreting power maps for PALs taken with different instruments.

A new portable digital meniscometer.

PURPOSE: The aims of this study were (i) to develop a new portable slit-lamp mounted digital meniscometer (PDM) and (ii) to test its accuracy and repeatability compared to the existing Yokoi et al. videomeniscometer (VM). METHODS: We developed a novel application for an iPod or iPhone, which created an illuminated target of parallel black and white bands. This was used as a portable device with which to perform reflective meniscometry. The medians of three consecutive measurements on five glass capillaries (internal radii, 0.100 to 0.505 mm) were compared between VM and PDM at two different sessions. Also, the central lower tear meniscus radius (TMR) in 20 normal subjects (10 males and 10 females; mean [SD] age, 32.3 [9.3] years) was measured using both techniques. Correlations between the instruments were analyzed using the Pearson coefficient. Differences between sessions and instruments were analyzed using Bland-Altman plots, coefficient of repeatability, and paired t-tests. RESULTS: The PDM and VM were accurate in vitro (95% confidence interval [CI] of difference: PDM -0.0134 to +0.0074 mm, p = 0.468; VM -0.0282 to + 0.0226 mm; p = 0.775) and reproducible between sessions (95% coefficient of repeatability, 0.019 and 0.018, respectively). The mean difference between the PDM and VM in vitro was 0.0002 mm (95% CI, -0.0252 to + 0.0256; p = 0.984). In human subjects, mean (SD) TMR measured with the PDM (0.34 [0.10] mm) and VM (0.36 [0.11] mm) was significantly correlated (r = 0.940; p < 0.001), and there was no statistically significant difference between the measured TMR of the instruments (p = 0.124). CONCLUSIONS: This new slit-lamp mounted digital meniscometer produces accurate and reliable measurements and provides similar values for tear meniscus radius, in human studies, to the existing VM. The instrument is suitable for use in both research and clinical practice.

Manufacturer changes lead to clinically important differences between two editions of the TNO stereotest.

PURPOSE: Stereoacuity tests used in clinical practice should be repeatable and reproducible. However, it has been observed in a clinical setting that new editions of the TNO stereotest appear to give different values from those obtained using previous versions. The purpose of the present research was to investigate this observation. METHODS: One hundred and twenty-one Dutch subjects, 88 (73%) females and 33 (27%) males, with an average age of 34.0 years (range 18-55) had their stereoacuity measured using two different versions of the TNO stereoacuity test (TNO 13 and TNO 15). The TNO was tested in a counterbalanced order so that consecutive subjects started with alternate editions to avoid bias. RESULTS: There was a significant difference (p < 0.001) between the median value for stereoacuity measured with TNO 13 (30 s of arc) and TNO 15 (60 s of arc). The bias between the two test versions was -0.23 Log arcseconds (95% limits of the differences: 0.15 to -0.60 Log arcseconds). CONCLUSION: This study reveals that results obtained with two different editions of a commonplace stereoacuity test are not comparable. New versions come on the market at regular intervals and the assumption that they will give the same results as previous versions may not be valid. Besides the statistically significant difference between the TNO 13 and TNO 15, the Bland-Altman plot also showed a considerable bias and the 95% limits of the differences between the TNO 13 and TNO 15 are more than two steps on the Log arcsecond scale. This difference between two editions of the TNO stereotests is not clinically acceptable and therefore it is inappropriate to use the two versions of the test interchangeably. It is important in both research and clinical records to specify the edition of the TNO test used.

Application of clinical techniques relevant for glaucoma assessment by optometrists: concordance with guidelines.

PURPOSE: Guidelines for the screening, prognosis, diagnosis, management and prevention of glaucoma were released by the Australian National Health and Medical Research Council in 2010. Comparable guidance has been made available by respective bodies in the USA and UK at a similar time. Key to successful translation of guidelines into clinical practice includes clinicians having the necessary skills to perform required tests. Optometrists in Australia and New Zealand were invited to participate in an online survey exploring these aspects. The results provide insights for improving glaucoma diagnosis and management by optometric primary eye care practitioners. METHODS: An online questionnaire was developed to investigate glaucoma assessment of optometrists as a function of demographic details, educational background and experience. Key points to ascertain compliance with current guidelines were the availability of equipment, procedural confidence in techniques, and preferences in visual field tests. Chi square statistics was employed to support similarity to national averages and highlight differences between the two countries. Multivariate linear regression analysis identified variables significantly associated with individual tests being available to optometrists and their confidence in applying them. RESULTS: Thirteen per cent of all Australian and 36% of the New Zealand optometrists responded to the survey in 2013, which reflected the demographics/geography of the practising populations. Techniques considered essential or preferred for glaucoma assessment were widely available in both countries with the exception of gonioscopy and pachymetry. After correcting for availability, regression models highlighted therapeutic endorsement and knowledge of glaucoma guidelines as the main variables to maintain high diagnostic confidence. Correlations to number of years in optometric practice mirrored a changed emphasis in teaching and technology over the past 10-15 years. CONCLUSIONS: Australian and New Zealand optometrists were well equipped to perform glaucoma assessments with the possible exception of gonioscopy. Advanced imaging modalities were not yet fully integrated into optometric practice, although optical coherence tomography has shown use by 23-32% of optometrists. A marked increase in use, availability and procedural confidence of gonioscopy and other techniques with therapeutically endorsed optometrists demonstrates the advantage and importance of additional training.

A survey of current and anticipated use of standard and specialist equipment by UK optometrists.

PURPOSE: To investigate current and anticipated use of equipment and information technology (IT) in community optometric practice in the UK, and to elicit optometrists' views on adoption of specialist equipment and IT. METHODS: An anonymous online questionnaire was developed, covering use of standard and specialist diagnostic equipment, and IT. The survey was distributed to a random sample of 1300 UK College of Optometrists members. RESULTS: Four hundred and thirty-two responses were received (response rate = 35%). Enhanced (locally commissioned) or additional/separately contracted services were provided by 73% of respondents. Services included glaucoma repeat measures (30% of respondents), glaucoma referral refinement (22%), fast-track referral for wet age-related macular degeneration (48%), and direct cataract referral (40%). Most respondents (88%) reported using non-contact/pneumo tonometry for intra-ocular pressure measurement, with 81% using Goldmann or Perkins tonometry. The most widely used item of specialist equipment was the fundus camera (74% of respondents). Optical Coherence Tomography (OCT) was used by 15% of respondents, up from 2% in 2007. Notably, 43% of those anticipating purchasing specialist equipment in the next 12 months planned to buy an OCT. 'Paperless' records were used by 39% of respondents, and almost 80% of practices used an electronic patient record/practice management system. Variations in responses between parts of the UK reflect differences in the provision of the General Ophthalmic Services contract or community enhanced services. There was general agreement that specialised equipment enhances clinical care, permits increased involvement in enhanced services, promotes the practice and can be used as a defence in clinico-legal cases, but initial costs and ongoing maintenance can be a financial burden. Respondents generally agreed that IT facilitates administrative flow and secure exchange of health information, and promotes a state-of-the-art practice image. However, use of IT may not save examination time; its dynamic nature necessitates frequent updates and technical support; the need for adequate training is an issue; and security of data is also a concern. CONCLUSION: UK optometrists increasingly employ modern equipment and IT services to enhance patient care and for practice management. While the clinical benefits of specialist equipment and IT are appreciated, questions remain as to whether the investment is cost-effective, and how specialist equipment and IT may be used to best advantage in community optometric practice.

Intraocular lens implantation position sensitivity as a function of refractive error.

PURPOSE: To quantify the change in ocular aberrations due to intraocular lens (IOL) implantation position errors for pseudo-phakic eyes with different refractive errors. METHODS: The theoretical part of this work was based on ray-tracing in emmetropic and myopic eye models. The possible misalignments i.e. the decentration, tilt and axial translation, of the IOLs were statistically combined together and analysed using Monte-Carlo simulations. Spherical IOLs with a 3 and 5 mm pupil and an aspheric IOL with a 5 mm pupil were analysed as a function of refractive error. In the experimental part of the work, we built an IOL optical test bench including a model eye. The white light discrete point spread functions of misaligned IOLs were recorded by a CCD and we compared the change of the spread function as a result of misalignments for two spherical IOLs with different optical powers. RESULTS: The Monte-Carlo simulations showed that the average root-mean-square spot size at the retinal plane decreased with increasing myopic refractive error, i.e. lower power IOL. The experiments showed that a lower optical power spherical IOL had a less distributed point spread function than a higher optical power IOL, which supported the results of the simulation. CONCLUSION: Regarding IOLs designed for myopic patients, low power IOLs (for high myopes) were shown to be less sensitive to the misalignment than high power ones. Aspheric IOLs were more sensitive to position errors than spherical IOLs under the same conditions.

[Contemporary applications of wavefront aberrometry in ophthalmology practice]. / Wspólczesne zastosowania aberrometrii w praktyce okulistycznej.

The aim of the article is to present and summarize the current knowledge of wavefront aberrations, methods and applications of aberrations measurement. Ideal optical system is stygmatic, which means that object point is imaged by optical system into the image point without deformation. Optical system of the eye is not ideal, it has aberrations. Aberrations limitate and determine visual quality. Wavefront aberrometers measure manochromatic low and high order aberrations. Wavefront aberrations are described by Zernike polinomials. More important wavefront sensor types are described in the article. In their practice authors use KR1W Topcon aberrometer. Authors also present difficulties in taking aberrometric measurements. In recent years quality of vision becomes the point of interest for vision scientists. Correction of high order aberrations is the future of optics.

The repeatability of the Goldmann-Weekers adaptometer for measuring cone adaptation.

To assess the inter-session repeatability of the Goldmann-Weekers adaptometer for the measurement of cone dark adaptation in a population of healthy subjects. Data were obtained from 31 healthy adults (mean age 21.5 ± 2.5) on 2 days. At each visit, pupils were dilated and a 96% bleach of cone photopigment was administered to the test eye before threshold was monitored continuously for 5 min in the dark using the Goldmann-Weekers adaptometer. A single exponential function was fitted to the threshold recovery data on a least squares basis. The coefficient of repeatability (CoR) was calculated to assess the repeatability of the time constant of recovery (τ), initial threshold and final threshold. Cone dark adaptation functions were successfully recorded from all subjects on both visits. The CoR was 79.48 s for τ, 0.71 log cdm(-2) for the initial threshold, and 0.58 log cdm(-2) for the final threshold. Paired samples t-tests showed that there were no significant differences between visits for any of the parameters assesed. Although the Goldmann-Weekers adaptometer was capable of monitoring the rapid changes in threshold that occur during cone dark adaptation, the CoR for τ was relatively large compared to the mean recovery time constants (126.48 ± 40.33 and 119.94 ± 33.25 s at the first and second visits, respectively). This indicates that the Goldmann-Weekers adaptometer is unlikely to be a useful instrument to chart changes in an individual's vision over time.