I feel sorry for your worker.I would like to give you this information taken from Qatar labor law.

Article(109)
The worker who sustains a work injury shall be entitled to receive medical treatment appropriate to his condition at the cost of the employer in accordance with the decision of the competent medical authority. He shall receive his full wage during the treatment period or the period of 6-months whichever is nearer. If the treatment continues for a period exceeding 6-months, the worker shall be paid half of his wage until his recovery or proof of permanent disability or death or whichever is nearer.

Article(110)
The worker who dies because of the work and the worker who SUSTAINS A WORK INJURY resulting in a partial or total permanent disability shall be entitled to receive compensation..........

Article(113)
The right of the worker to claim compensation for the disability or death shall extinguish by the lapse of 1-year from the date of the medical report containing the occurence of the disability resulting from injury..........

Since you are coming to Doha, the best place you contact first is your embassy to seek assistance.
Second, your worker needs a MEDICAL REPORT from Hamad Hospital and POLICE REPORT which contents a brief description of the incident. He may need also a witness to sign and testify the accident(can be one of his colleagues at the site).
Third, the address of Labor dept. at Almuntazah area along C-ring road just besides American Hospital.
Fourth, sorry i cant help you w/ the best lawyer, you can ask assistance from your embassy in this. And you may also want to know the degree of disability of your worker: Loss of vision in one eye(completely)= 50%

I wish for your worker quick recovery. Any additional advice for tieusufu?