City inspectors believe the cause of eye irritation at a Northeast Philadelphia cheerleading competition earlier this month was from ultraviolet light from a defective light.

More than 150 people who attended the event at Father Judge High School on Dec. 4 showed up at area hospitals complaining of eye problems.

The school was closed by the Archdiocese of Philadelphia while health officials made sure that there was no chemical or biological contamination in the school's gymnasium, where about 1,000 people attended the competition.

The school, located on Solly Avenue in the city's Holmesburg section, was reopened Dec. 8.

In a letter Wednesday to those who attended, a city health official said inspectors had found a defective metal halide lamp in the gym's ceiling.

The light exposed people to ultraviolet light, which apparently caused photokeratitis, wrote Dr. Steven Alles. Photokeratitis is painful but temporary.

Contact staff writer Robert Moran at 215-854-5983 or bmoran@phillynews.com.