An observational study in Presbyopia, sponsored by Gemini Eye Clinic. Completed at 1 site in Czechia. Per ClinicalTrials.gov, last updated 2026-06-03.
Sponsored by Gemini Eye Clinic · Observational
The objective of the study is to assess the long-term safety and effectiveness of the CorVision® microlens implanted in presbyopic patients for the management of management of presbyopia and near vision impairment. Approximately 100 patients in the Czech Republic will participate in this study. The study was reviewed and approved by an independent research ethics committee and also by the State Institute for Drug Control (SÚKL). The study will consist of a single visit during which standard, non-invasive, and painless examinations will be performed. This visit will correspond to the 4-year follow-up visit of the original clinical trial.
The target population are patients who suffered from presbyopia and underwent the original CorVision clinical study are medically suitable to undertake the current clinical study investigation.
Exclusion Criteria:
Presbyopic patients who have undergone implantation of the CorVision microlens according to study protocol CMG-PRT-002.
Uncorrected Near Visual Acuity of 0.3 logMAR or better
More than 65% of the eyes should have an Uncorrected Near Visual Acuity (UNVA) of 0.3 logMAR or better at 4 years postoperatively.
Time frame: At least 4 years after the implantation
Implant removal
The incidence of implant rejection leading to implant removal should occur in no more than 3% of implanted eyes.
Time frame: At least 4 years after the implantation
Clinically significant corneal haze occurrence
Clinically significant corneal haze is defined as any new stromal clouding in or near the laser-created pocket that leads to a reduction in central corneal clarity/transparency, is visible upon slit-lamp examination, and is graded as ≥ 2 on a standardized corneal haze grading scale.
Time frame: At least 4 years after the implantation
Monocular Uncorrected Near Visual Acuity at Best Reading Distance
Change in monocular uncorrected near visual acuity and best reading distance over time
Time frame: At least 4 years after the implantation
Monocular and Binocular Uncorrected Near Visual Acuity at 40 cm
Change in monocular and binocular Uncorrected Near Visual Acuity (UNVA) at 40 cm.
Time frame: At least 4 years after the implantation
Monocular and Binocular Distance Corrected Near Visual Acuity
Change in monocular and binocular Distance Corrected Near Visual Acuity (DCNVA).
Time frame: At least 4 years after the implantation
Monocular and Binocular Corrected Near Visual Acuity
Change in monocular and binocular Corrected Near Visual Acuity (CNVA) over time.
Time frame: At least 4 years after the implantation
Monocular and Binocular Uncorrected Intermediate Visual Acuity (UIVA)
Change in monocular and binocular Uncorrected Intermediate Visual Acuity (UIVA) over time.
Time frame: At least 4 years after the implantation
Monocular and Binocular Distance Corrected Intermediate Visual Acuity
Change in monocular and binocular Distance Corrected Intermediate Visual Acuity (DCIVA) over time.
Time frame: At least 4 years after the implantation
Monocular and Binocular Uncorrected Distance Visual Acuity (UDVA)
Change in monocular Uncorrected Distance Visual Acuity (UDVA) over time.
Time frame: At least 4 years after the implantation
Monocular and Binocular Corrected Distance Visual Acuity (CDVA)
Change in monocular and binocular Corrected Distance Visual Acuity (CDVA) over time.
Time frame: At least 4 years after the implantation
Objective refraction
Change in objective refractive sphere and cylinder magnitude measured by autorefractometry.
Time frame: At least 4 years after the implantation
Subjective refraction
Change in manifest refractive sphere and cylinder magnitude, measured in diopters (D).
Time frame: At least 4 years after the implantation
Near addition
Change in near addition values over time.
Time frame: At least 4 years after the implantation
Corneal Keratometry Measurements (K1, K2, and Kmean)
Change in corneal keratometry values, including K1, K2, and mean keratometry (Kmean), as measured by corneal topography over time. Change in keratometry K1, K2 and Kmean measured in diopters over time.
Time frame: At least 4 years after the implantation
Central Corneal Thickness (Pachymetry) Measurement
Change in central corneal thickness as measured by corneal pachymetry over time.
Time frame: At least 4 years after the implantation
Endothelial Cell Density (Study Eye)
Change in endothelial cell density over time.
Time frame: At least 4 years after the implantation
Intraocular Pressure (Study Eye)
Change in intraocular pressure over time.
Time frame: At least 4 years after the implantation
Tear Film Break-Up Time (TBUT) Test
Change in tear film stability as measured by Tear Film Break-Up Time (TBUT) in units of seconds.
Time frame: At least 4 years after the implantation
Tear Production (Schirmer Test)
Change in tear production as measured by the Schirmer test in units of mm.
Time frame: At least 4 years after the implantation
Corneal Thickness Measurement Using Optical Coherence Tomography (OCT)
Change in corneal thickness measured at the corneal center in μm.
Time frame: At least 4 years after the implantation
Abnormal findings at OCT
Incidence of abnormal findings on OCT.
Time frame: At least 4 years after the implantation
Slit-lamp findings
Incidence of abnormal slit lamp findings (eyelid, conjunctiva, epithelium, stroma, central cornea clarity, cornea neovascularization, anterior chamber, iris, lens).
Time frame: At least 4 years after the implantation
Contrast sensitivity
Determination of contrast sensitivity measured by CSV 1000 (Vector Vision) (changes from the pre-operative to the post-operative state and its stability over time will be investigated).
Time frame: At least 4 years after the implantation
Defocus curve
Change in visual acuity measured at different defocus vergence levels during monocular defocus curve testing over time.
Time frame: At least 4 years after the implantation
Aberrometry measurements using iTrace
Change in the total higher order aberrations (HOA) assessed by iTrace.
Time frame: At least 4 years after the implantation
Subjective questionnaire QoV - patient satisfaction
Evaluation of patient satisfaction assessed on a scale
Time frame: At least 4 years after the implantation
Subjective questionnaire QoV
Evaluation of patient satisfaction as assessed using the Quality of Vision (QoV) questionnaire scoring scale.
Time frame: At least 4 years after the implantation
Adverse events incidence
Intraoperative and adverse events at each time point (numbers and percentages)
Time frame: At least 4 years after the implantation
This study is completed, as verified in May 2026. You cannot join it, but the record below documents what was studied.
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