Specvis: Free and open-source software for visual field examination

<div><p>Visual field impairment affects more than 100 million people globally. However, due to the lack of the access to appropriate ophthalmic healthcare in undeveloped regions as a result of associated costs and expertise this number may be an underestimate. Improved access to affordable diagnostic software designed for visual field examination could slow the progression of diseases, such as glaucoma, allowing for early diagnosis and intervention. We have developed Specvis, a free and open-source application written in Java programming language that can run on any personal computer to meet this requirement (<a href="http://www.specvis.pl/" target="_blank">http://www.specvis.pl/</a>). Specvis was tested on glaucomatous, retinitis pigmentosa and stroke patients and the results were compared to results using the Medmont M700 Automated Static Perimeter. The application was also tested for inter-test intrapersonal variability. The results from both validation studies indicated low inter-test intrapersonal variability, and suitable reliability for a fast and simple assessment of visual field impairment. Specvis easily identifies visual field areas of zero sensitivity and allows for evaluation of its levels throughout the visual field. Thus, Specvis is a new, reliable application that can be successfully used for visual field examination and can fill the gap between confrontation and perimetry tests. The main advantages of Specvis over existing methods are its availability (free), affordability (runs on any personal computer), and reliability (comparable to high-cost solutions).</p></div

Summary averaged test duration, fixation accuracy (FA) and false-positive response rate (FPRR) for individual subjects from all three groups each using different fixation monitor technique, i.e. <i>Blindspot</i>, <i>Fixation point change</i>, and <i>Both</i>.

<p>Averaging was performed for the results from six individual inter-subject visual field examinations.</p

Window for optional adjustment of screen and luminance scales.

<p>The user can adjust settings for the chosen screen as well as configure and set luminance scales for the stimulus or background.</p

Comparison of Specvis results from two separate visual field examination days.

<p><b>A and B</b>. MM700 and Specvis results (respectively) acquired in one day, say “day zero”. <b>C and D</b>. MM700 and Specvis results (respectively) acquired also in one day, but 20 days after “day zero”. <b>E</b>. Comparison of Specvis results from both aforementioned days by means of subtraction. Conventions are the same as in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0186224#pone.0186224.g003" target="_blank">Fig 3</a>.</p

The initial Specvis window.

<p>After launching Specvis, this first window will be displayed and the user can add, choose or edit patient details, as well as preview their previous results. It is also possible to load a default template for settings if the user does not wish to do this manually.</p

Window for previewing the quality of fit for the chosen luminance scale.

<p>The user can check the chosen luminance scale for goodness of fit, in the context of how accurate is the relation between luminance expressed in cd/m² and brightness expressed in the HSB space. The quality of the scale can be assessed based on the chi-squared statistic and its significance (p-value), as well as the standard deviation (SD).</p

Glaucomatous patient no. 4; Medmont M700 (MM700) and Specvis visual field graphical maps.

<p><b>A</b>. The results from MM700 were mapped according a decibel scale (dB) where NO indicates a lack of response to the stimulus in predefined locations. <b>B and C</b>. Visual field sensitivity obtained with the Specvis application shown as gray scale or color scale graphical maps in dB for easy comparison to the MM700 maps. The white X marker indicates the location for fixation control testing and therefore also represents the location of the optic disc. Axes intersect at the fixation point with tick marks at 10° intervals.</p

Window for adjusting fixation and other options.

<p>In this window the user sets the fixation point characteristics, measure its luminance, and set its position on the screen. At this level, the user can also choose and adjust the fixation monitor technique (<i>Blindspot</i>, <i>Fixation point change</i>, <i>Both</i>), as well as the procedural algorithm (<i>Basic</i>) that will be used in the visual field examination test. Keyboard configuration can also be changed here.</p

Patients’ general information.

<p>Visual acuity of glaucomatous (GM) patients were tested with the use of Snellen charts (5 m for best corrected visual acuity/ uncorrected visual acuity (BCVA/UVA) and 30 cm for corrected near visual acuity/ uncorrected near visual acuity (CNVA/UNVA)) at the Mega-Lens Specialized Ophthalmology Clinic in Warsaw. The intra-ocular pressure (IOP) of glaucomatous patients was also measured in the clinic. Visual acuity of retinitis pigmentosa (RP) patient was tested at the Nencki Institute of Experimental Biology of the Polish Academy of Sciences in Warsaw with the use of Early Treatment Diabetic Retinopathy Study (ETDRS) charts (5 m for BCVA/UVA and 33 cm for CNVA/UNVA). Visual acuity results are expressed in Visus scale (also known as Snellen scale).</p

Window used for optional adjustments of the stimulus and background.

<p>The user can adjust settings for the stimulus and background, as well as preview the stimulus distribution on the previously chosen screen.</p