My Offers

Please contact me.

Lectures and Seminars

My seminars and lectures are specialized in binocular vision and optometric methods, but I also cover basic knowledge. I generally refer to the current, evidence-based state of knowledge:

• Optometric eye examinations, subjective and objective
• Binocular measurement methods such as MKH or Mallett (see my youtube cannel)
• Special binocular topics such as near vision testing or microstrabismus
• Binocular screening for schoolchildren
• Classification of non-strabismic anomalies (Integrative Analysis)
• Examination methods for strabismus
• Pediatric optometry
• Examinations for schoolchildren with reading and spelling difficulties

I give lectures and seminars on conferences and for companies and events. For example, at the European Academy of Optometry and Optics (eaoo), the Zeiss Academy in the Netherlands, and the HOYA Faculty Training in Budapest and St. Petersburg.

Dates, topics, and prices upon request:

info(at)bino-expert.com

Optometric Eye Examinations

At my practice, opti-school, I conduct optometric eye examinations with a focus on prescription eyeglasses according to best practice and to a high standard: for new prescriptions and/or as a second opinion.

Research and Publications

Publications

The textbook "Binocular Correction. MCH in Theory and Practice" is available from DOZ Verlag in German. The 3rd edition has been completely revised and costs €69.90.

A few copies of the English translation of the previous edition are still available from me under the title “Binocular Correction” upon request.  
Schroth, V. (2012). Binocular Correction. Aligning prisms according to the Haase approach. Heemskerk, The Netherlands, Zijdar Book.

List of Publications sorted by year of publication

Schroth, V. (1998). Erfolgsbeobachtung: Prismenkorrektion bei Kindern, die nicht freiwillig lesen. Neues Optikerjournal, NOJ. 21-22.

​Schroth, V. (1999). Die LEGAMU Studie; Prismenbrillen bei Legasthenie. Optometrie. Mainz, WVAO. 4.

Gerling, J., et al. (2000). "[Can fixation disparity be detected reliably by measurement and correctional techniques according H.J. Haase (MKH)?]." Klin Monbl Augenheilkd 216(6): 401-411.

BACKGROUND: The theory of the "Measuring and Correction Methods of H.-J. Haase" (MCH) states that a small misalignment of one eye, called fixation disparity, indicates a difficulty in overcoming a "vergence position of rest" that is different from ortho position. This difficulty, so the theory, can cause asthenopic complaints, such as headaches, and these complaints can be relieved by prisms. The theory further claims that fixation disparity can be ascertained by a series of tests which depend on the subject's perception. The tests most decisive for the diagnosis of a so-called fixation disparity type 2 consist of stereo displays. The magnitude of the prism that allows the subject to see the test configurations in symmetry is thought to be the one that corrects the "vergence position of rest". METHODS: Nine subjects with healthy eyes in whom a "fixation disparity type 2" had been diagnosed were selected for the study. Misalignment of the eyes was determined according to the principle of the unilateral cover test. Targets identical for both eyes were presented on the screen of the Polatest E. Then, the target was deleted for one eye and the ensuing position change of the other eye was measured, using the search coil technique. This test was performed both with and without the MCH prism. RESULTS: In all 9 subjects the misalignment was less than 10 minutes of arc, i.e. in the range of normal fixation instability. Averaging across the 9 subjects, the deviation of the eye (misaligned according to MCH) was 0.79 +/- 3.45 minutes of arc in the direction opposed to that predicted by the MCH, a value not significantly different from zero. The MCH prism elicited a fusional vergence movement the magnitude of which corresponded to the magnitude of the MCH prism. CONCLUSION: Ascertaining fixation disparity with the MCH is unreliable. Accordingly, it appears dubious to correct a "vergence position of rest" on the basis of the MCH.

Schroth, V. (2001). Der WS Lesetest und seine Anwendung in der Optometrie. Optometrie. Mainz, WVAO. 1.

Schroth, V. (2002). Farbgläser bei Sehproblemen. Der Augenoptiker. Leinfelden Echterdingen, Konradin Verlag. 2.

Schroth, V. (2003). Visuelle Probleme und ihre Korrektion mit Farben. Juvemus Mitgliederzeitschrift. Koblenz, Juvemus e.V. 11.

Schroth, V. (2005). Theorie der MKH - Neue wissenschaftlichen Erkenntnisse zu FD, Stereopsis und Prävalenz. Deutsche Optikerzeitung. Heidelberg, DOZ Verlag. 12.

Schroth, V. and W. Jaschinski (2006). "Assozierte Heterophorie und Vorn-hinten-Asymmetrie der Prävalenz eines Auges." Klin Monatsbl Augenheilkd 223(03): 233-242.

Schroth, V. and W. Jaschinski (2007). "Beeinflussen Prismen nach H.-J. Haase die Augenprävalenz?" Klin Monatsbl Augenheilkd 224(01): 32-39.

Schroth, V. (2007). Pilotstudie zum Einfluss von Winkelrechtsichtigkeit auf gute Handschrift und sehr gute Leseleistung. Deutsche Optikerzeitung. Heidelberg, DOZ Verlag. 3: 42-49.

Jaschinski, W. and V. Schroth (2008). "Ocular prevalence: difference between crossed and uncrossed disparities of stereo objects." Strabismus 16(4): 159-164.     

Schroth, V. (2012). Binocular Correction. Aligning prisms according to the Haase approach. Heemskerk, The Netherlands, Zijdar Book.

Schroth, V., et al. (2015). "Effects of Prism Eyeglasses on Objective and Subjective Fixation Disparity." PLoS One 10(10): e0138871.

    In optometry of binocular vision, the question may arise whether prisms should be included in eyeglasses to compensate an oculomotor and/or sensory imbalance between the two eyes. The corresponding measures of objective and subjective fixation disparity may be reduced by the prisms, or the adaptability of the binocular vergence system may diminish effects of the prisms over time. This study investigates effects of wearing prisms constantly for about 5 weeks in daily life. Two groups of 12 participants received eyeglasses with prisms having either a base-in direction or a base-out direction with an amount up to 8 prism diopters. Prisms were prescribed based on clinical fixation disparity test plates at 6 m. Two dependent variables were used: (1) subjective fixation disparity was indicated by a perceived offset of dichoptic nonius lines that were superimposed on the fusion stimuli and (2) objective fixation disparity was measured with a video based eye tracker relative to monocular calibration. Stimuli were presented at 6 m and included either central or more peripheral fusion stimuli. Repeated measurements were made without the prisms and with the prisms after about 5 weeks of wearing these prisms. Objective and subjective fixation disparity were correlated, but the type of fusion stimulus and the direction of the required prism may play a role. The prisms did not reduce the fixation disparity to zero, but induced significant changes in fixation disparity with large effect sizes. Participants receiving base-out prisms showed hypothesized effects, which were concurrent in both types of fixation disparity. In participants receiving base-in prisms, the individual effects of subjective and objective effects were negatively correlated: the larger the subjective (sensory) effect, the smaller the objective (motor) effect. This response pattern was related to the vergence adaptability, i.e. the individual fusional vergence reserves.

Schroth, V., et al. (2017). "Hoya Eyegenius®: New Method for Measuring and Correcting Fixation Disparity." Proceedings of the Latvian Academy of Sciences. Section B. Natural, Exact, and Applied Sciences. 71(5): 392-396.

    Abstract: Many things interfere with good binocular vision in nowadays modern digital environment: long periods spent looking at screens and switching between different digital devices at short distances. Vision-related or asthenopic complaints such as headaches, tired and burning eyes or blurred vision can be experienced by many people. Prescribing prismatic correction for fixation disparity can help to reduce these symptoms. A new, highly innovative method for measuring and correcting fixation disparity has been developed - HOYA EyeGenius®. The HOYA EyeGenius® method includes the unique examination procedures, pre-tests and fixation disparity measurements at far and near distances. The pre-tests allow to include patients with asthenopic complaints only with normal binocular vision and exclude cases with abnormal binocular vision. The main innovation of EyeGenius is based on direct conversion of the fixation disparity value into a prism amount. Therefore, the trial prismatic lenses are not used during the test. The use of digital devices makes this method interactive and minimizes the influence of the examiner.

Schroth, V., et al. (2019). "Short-term effects of aligning prisms on the objective and subjective fixation disparity in far distance." https://bop.unibe.ch/JEMR 12(4). 

    Fixation disparity (FD) refers to a suboptimal condition of binocular vision. The oculomotor aspect of FD refers to a misadjustment in the vergence angle between the two visual axes that is measured in research with eye trackers (objective fixation disparity, oFD). The sensory aspect is psychophysically tested using dichoptic nonius lines (subjective fixation disparity, sFD). Some optometrists use nonius tests to determine the prisms for constant wear aiming to align the eyes. However, they do not (yet) use eye trackers. We investigate the effect of aligning prisms on oFD and sFD for 60 sec exposure duration of prisms determined with the clinically established Cross test in far distance vision. Without prisms, both types of FD were correlated with the aligning prism, while with prisms the FD was close to zero (these analyses included all base-in and base-out cases). The effect of base-in prisms on oFD was proportional to the amount of the aligning prism for the present 60 sec exposure, similar as for the 2- 5 sec exposure in Schmid et al. (2018). Thus, within 1 minute of prism exposure, no substantial vergence adaptation seems to occur in the present test conditions. Further studies may investigate intra- individual responses to different exposure times of aligning prisms in both prism directions.

Schroth, V. (2021). Binokulare Korrektion; MKH in Theorie und Praxis. Heidelberg, DOZ Verlag.

Neuenschwander, E. R., Laura und Schroth, Volkhard (2021). "Veränderung des NPC bei Personen mit Konvergenzinsuffizienz nach I.F.S.-Visualtraining." Optometry & Contact Lenses 1(No. 5): 156-163.

Schroth, V. (2022). "Update zur Fixationsdisparität." Optometry & Contact Lenses Vol. 2(Nr. 4): 120-126.

Knobel, X. S., Volkhard (2024). Binokulare Auffälligkeiten erkennen und korrigieren. Die minimale Testbatterie und die BTSO-Lern-App. Schweizer Optiker. 3: 16-21.