The Effects of Primary Pterygium on Contrast Sensitivity Preoperatively and Postoperatively

Primary Pterygium Clinical Trial

Official title:

The Effects of Primary Pterygium on Contrast Sensitivity Preoperatively and Postoperatively

Clinical Trial Details — Status: Recruiting

Administrative data

• NCT number: NCT03406390
• Other study ID #: 2017011
• Status: Recruiting
• Phase: N/A
• First received: November 3, 2017
• Last updated: January 13, 2018
• Start date: November 1, 2017
• Est. completion date: December 31, 2018

Study information

• Verified date: January 2018
• Source: Zhongshan Ophthalmic Center, Sun Yet-sen University
• Contact: Jing Zhong, Doctor
• Phone: 13527841235
• Email: zhongjing_90[@]163.com
• Is FDA regulated: No
• Study type: Observational

Clinical Trial Summary

Pterygium is the growth of conjunctival tissue onto the cornea, usually from the nasal quadrant of the cornea.Visual acuity may be reduced due to direct invasion of the visual axis or astigmatism induced by the pterygium. Contrast sensitivity measures two variables, size, and contrast which could comprehensively reflect the visual quality of the primary pterygium patients. In this study, we would investigate the the effects of primary pterygium on contrast sensitivity preoperatively and on the 1st, 3rd and 6th month postoperatively, moreover, the related parameters on the contrast sensitivity in the primary pterygium patients would be analyzed.

Description:

There would have two groups included in our study, which are primary pterygium group(40 patients) and the normal group (20 volunteers). The inclusion criteria for the primary pterygium group were: 1) more than 18 and less than 60 years old; 2)diagnosed as primary pterygium by the professional doctor; 3)0.0 or better logMAR BCVA; 4) absence of other ocular disorders and no history of eye surgery and other systemic diseases. The inclusion criteria for the normal group were: 1) between 18 and 60 years old; 2) 0.0 or better logMAR BCVA;3) no history of any ocular pathology, and normal physical and mental health.

All the subjects would receive the ophthalmic examination and contrast sensitivity test (quick contrast sensitivity function, quick CSF), in which the pterygium group would achieve the pterygium surgery by the same surgeon (Jin Yuan) and then be performed the contrast sensitivity test on the 1st, 3rd and 6th month postoperatively.

The quick CSF method, implemented in a 10 alternative forced-choice digit identification task, was used to assess the contrast sensitivity function34, 38. Stimuli were displayed on a gamma-corrected 46 inch LCD monitor (Model: NEC LCD P463) with a 1920×1080 pixel resolution, 50 cd/m2 mean luminance and 60 Hz vertical refresh rate. Observers viewed the display monocularly from a distance of 4 m in a dark room. For each trial, they were asked to verbally report the identities of three digits presented on the screen to the experimenter, who used the computer keyboard to enter their responses. The stimuli disappeared after all the responses were entered. Observers were given the option to report ''I don't know'' upon which the response was coded as incorrect. No feedback was provided. All three responses were used to update the posterior distribution of the CSF parameters, which in turn was used to adaptively choose the most informative combination of spatial frequency and contrast for the next trial. A new trial started 500 ms after the responses. There were 30 trials in approximately 5 min. The quick CSF data were scored to generate the cutoff spatial frequency, defined as the spatial frequency corresponding to a perceptual sensitivity of 1, and the area under the log CSF (AULCSF), a summary measure of the window to spatial vision

Recruitment information / eligibility

• Status: Recruiting
• Enrollment: 60
• Est. completion date: December 31, 2018
• Est. primary completion date: November 1, 2018
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 20 Years to 60 Years

Eligibility

Inclusion Criteria:

• Clinical diagnosis of the primary pterygium;

• More than 18 and less than 60 years old;

• 0.0 or better logMAR BCVA;

• The absence of other ocular disorders and no history of eye surgery and other systemic diseases.

Exclusion Criteria:

• Clinical diagnosis of recurrent pterygium or accompanied with other ocular diseases;

• less than 18 or more than 60 years old;

• The logMAR BCVA is less than 0.0;

• With the history of eye surgery and other systemic diseases.

Related Conditions & MeSH terms

• Hypersensitivity
• Primary Pterygium
• Pterygium

Intervention

Procedure:
• Pterygium surgery
The patients were anesthetized with subconjunctival injection.Symblepharon was released and fibrotic tissue was extensively dissected to expose the sclera and corneal stroma. The subconjunctival fibrovascular tissue, including Tenon's capsule, were thoroughly removed using scissors from the sclera and medial rectus muscle at the area of the superior and inferior fornices and the nasal caruncle. A cryopreserved human amniotic membrane (Zhongshan Ophthalmic Center, China) was then placed on the entire exposed bare sclera with the epithelial side facing upward, and secured with 10-0 nylon sutures.

Locations

Country	Name	City	State
China	Zhongshan Opthalmic Center	Guangzhou	Guangdong

Sponsors (1)

Lead Sponsor	Collaborator
Zhongshan Ophthalmic Center, Sun Yet-sen University

Country where clinical trial is conducted

China, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	The contrast sensitivity function tested by quick CSF of the Primary Pterygium patients preoperatively	The contrast sensitivity function of the Primary Pterygium patients is lower than the normal people by qucik CSF method	Preoperatively
Secondary	The contrast sensitivity function tested by quick CSF of the Primary Pterygium patients postoperatively	The contrast sensitivity function of the Primary Pterygium patients is improved compared with the normal people by quick CSF method	1st, 3rd and 6th month postoperatively